diff --git a/src/main/java/Main.java b/src/main/java/Main.java
index 7b5c09a..1741553 100644
--- a/src/main/java/Main.java
+++ b/src/main/java/Main.java
@@ -9,7 +9,7 @@ import java.util.*;
 
 public class Main
 {
-    private static Logger log = Logger.getLogger(Main.class.getName());
+    private static final Logger log = Logger.getLogger(Main.class.getName());
 
     public static void main(final String[] args)
     {
@@ -23,8 +23,8 @@ public class Main
         final var dbInfo = new DatabaseInformation("localhost", "sourcedb1", "test", "test", 25003);
         final var connection = new ConnectionHelper(DatabaseType.MARIADB, dbInfo).createConnection();
 
-        DataStorer<PersonSource> personSourceDataStorer = (rs) -> {
-            var persons = new ArrayList<PersonSource>();
+        final DataStorer<PersonSource> personSourceDataStorer = (rs) -> {
+            final var persons = new ArrayList<PersonSource>();
             while (rs.next())
             {
                 persons.add(new PersonSource(
@@ -36,17 +36,17 @@ public class Main
             return persons;
         };
 
-        StatementPreparerExtractor statementPreparer = (preparedStatement) -> {
+        final StatementPreparerExtractor statementPreparer = (preparedStatement) -> {
         };
 
-        var sql = "select * from person;";
+        final var sql = "select * from person;";
 
         return new Extractor<>(connection, personSourceDataStorer, statementPreparer, sql).doExtract();
     }
 
-    private static List<CharacterTarget> testTransform(List<PersonSource> persons)
+    private static List<CharacterTarget> testTransform(final List<PersonSource> persons)
     {
-        DataTransformer<PersonSource, CharacterTarget> personTransformer =
+        final DataTransformer<PersonSource, CharacterTarget> personTransformer =
                 (personSource) -> new CharacterTarget(personSource.getPersonId(),
                 personSource.getName(),
                 personSource.isMortal());
@@ -54,18 +54,18 @@ public class Main
         return new Transformer<>(personTransformer, persons).doTransform();
     }
 
-    private static void testLoad(List<CharacterTarget> transformedData)
+    private static void testLoad(final List<CharacterTarget> transformedData)
     {
         final var dbInfo = new DatabaseInformation("localhost", "targetdb", "test", "test", 25001);
         final var connection = new ConnectionHelper(DatabaseType.POSTGRESQL, dbInfo).createConnection();
 
-        StatementPreparerLoader<CharacterTarget> statementPreparerLoader =  (preparedStatement, data) -> {
+        final StatementPreparerLoader<CharacterTarget> statementPreparerLoader =  (preparedStatement, data) -> {
             preparedStatement.setInt(1, data.getPersonId());
             preparedStatement.setString(2, data.getName());
             preparedStatement.setBoolean(3, data.isMortal());
         };
 
-        var sql = "insert into person values (?, ?, ?)";
+        final var sql = "insert into person values (?, ?, ?)";
 
         new Loader<>(connection, statementPreparerLoader, transformedData, sql).doLoad();
     }
diff --git a/src/main/java/data/source/AbilitiesSource.java b/src/main/java/data/source/AbilitiesSource.java
index 65f07be..8a3d755 100644
--- a/src/main/java/data/source/AbilitiesSource.java
+++ b/src/main/java/data/source/AbilitiesSource.java
@@ -4,11 +4,11 @@ import data.SourceDataset;
 
 public class AbilitiesSource implements SourceDataset
 {
-    private String name;
-    private String description;
-    private int level;
+    private final String name;
+    private final String description;
+    private final int level;
 
-    public AbilitiesSource(String name, String description, int level)
+    public AbilitiesSource(final String name, final String description, final int level)
     {
         this.name = name;
         this.description = description;
diff --git a/src/main/java/data/source/ActiveQuestsSource.java b/src/main/java/data/source/ActiveQuestsSource.java
index da4224c..e4caaad 100644
--- a/src/main/java/data/source/ActiveQuestsSource.java
+++ b/src/main/java/data/source/ActiveQuestsSource.java
@@ -4,10 +4,10 @@ import data.SourceDataset;
 
 public class ActiveQuestsSource implements SourceDataset
 {
-    private int questId;
-    private int progress;
+    private final int questId;
+    private final int progress;
 
-    public ActiveQuestsSource(int questId, int progress)
+    public ActiveQuestsSource(final int questId, final int progress)
     {
         this.questId = questId;
         this.progress = progress;
diff --git a/src/main/java/data/source/GameobjectSource.java b/src/main/java/data/source/GameobjectSource.java
index a8668da..7da9f03 100644
--- a/src/main/java/data/source/GameobjectSource.java
+++ b/src/main/java/data/source/GameobjectSource.java
@@ -4,11 +4,11 @@ import data.SourceDataset;
 
 public class GameobjectSource implements SourceDataset
 {
-    private int objectId;
-    private String name;
-    private String description;
+    private final int objectId;
+    private final String name;
+    private final String description;
 
-    public GameobjectSource(int objectId, String name, String description)
+    public GameobjectSource(final int objectId, final String name, final String description)
     {
         this.objectId = objectId;
         this.name = name;
diff --git a/src/main/java/data/source/InventorySource.java b/src/main/java/data/source/InventorySource.java
index 9376da0..b773642 100644
--- a/src/main/java/data/source/InventorySource.java
+++ b/src/main/java/data/source/InventorySource.java
@@ -4,9 +4,9 @@ import data.SourceDataset;
 
 public class InventorySource implements SourceDataset
 {
-    private int objectId;
+    private final int objectId;
 
-    public InventorySource(int objectId)
+    public InventorySource(final int objectId)
     {
         this.objectId = objectId;
     }
diff --git a/src/main/java/data/source/ModSource.java b/src/main/java/data/source/ModSource.java
index c65cef5..a44c43c 100644
--- a/src/main/java/data/source/ModSource.java
+++ b/src/main/java/data/source/ModSource.java
@@ -7,12 +7,12 @@ import java.time.LocalDate;
 
 public class ModSource implements SourceDataset
 {
-    private int modId;
-    private String name;
-    private LocalDate installationDate;
-    private Blob binary;
+    private final int modId;
+    private final String name;
+    private final LocalDate installationDate;
+    private final Blob binary;
 
-    public ModSource(int modId, String name, LocalDate installationDate, Blob binary)
+    public ModSource(final int modId, final String name, final LocalDate installationDate, final Blob binary)
     {
         this.modId = modId;
         this.name = name;
diff --git a/src/main/java/data/source/PersonInventorySource.java b/src/main/java/data/source/PersonInventorySource.java
index 7c87468..55d23ec 100644
--- a/src/main/java/data/source/PersonInventorySource.java
+++ b/src/main/java/data/source/PersonInventorySource.java
@@ -4,10 +4,10 @@ import data.SourceDataset;
 
 public class PersonInventorySource implements SourceDataset
 {
-    private int personId;
-    private int objectId;
+    private final int personId;
+    private final int objectId;
 
-    public PersonInventorySource(int personId, int objectId)
+    public PersonInventorySource(final int personId, final int objectId)
     {
         this.personId = personId;
         this.objectId = objectId;
diff --git a/src/main/java/data/source/PersonSource.java b/src/main/java/data/source/PersonSource.java
index 3df6ead..0f4f093 100644
--- a/src/main/java/data/source/PersonSource.java
+++ b/src/main/java/data/source/PersonSource.java
@@ -4,11 +4,11 @@ import data.SourceDataset;
 
 public class PersonSource implements SourceDataset
 {
-    private int personId;
-    private String name;
-    private boolean mortal;
+    private final int personId;
+    private final String name;
+    private final boolean mortal;
 
-    public PersonSource(int personId, String name, boolean mortal)
+    public PersonSource(final int personId, final String name, final boolean mortal)
     {
         this.personId = personId;
         this.name = name;
diff --git a/src/main/java/data/source/PlayerAbilitiesSource.java b/src/main/java/data/source/PlayerAbilitiesSource.java
index 04287e0..e4f3b04 100644
--- a/src/main/java/data/source/PlayerAbilitiesSource.java
+++ b/src/main/java/data/source/PlayerAbilitiesSource.java
@@ -4,10 +4,10 @@ import data.SourceDataset;
 
 public class PlayerAbilitiesSource implements SourceDataset
 {
-    private int playerId;
-    private int abilityId;
+    private final int playerId;
+    private final int abilityId;
 
-    public PlayerAbilitiesSource(int playerId, int abilityId)
+    public PlayerAbilitiesSource(final int playerId, final int abilityId)
     {
         this.playerId = playerId;
         this.abilityId = abilityId;
diff --git a/src/main/java/data/source/QuestSource.java b/src/main/java/data/source/QuestSource.java
index 826f27e..643c763 100644
--- a/src/main/java/data/source/QuestSource.java
+++ b/src/main/java/data/source/QuestSource.java
@@ -8,12 +8,12 @@ import java.util.Objects;
 
 public class QuestSource implements SourceDataset
 {
-    private int questId;
-    private String name;
-    private Clob dialogue;
-    private int personId;
+    private final int questId;
+    private final String name;
+    private final Clob dialogue;
+    private final int personId;
 
-    public QuestSource(int questId, String name, Clob dialogue, int personId)
+    public QuestSource(final int questId, final String name, final Clob dialogue, final int personId)
     {
         this.questId = questId;
         this.name = name;
@@ -42,7 +42,7 @@ public class QuestSource implements SourceDataset
     }
 
     @Override
-    public boolean equals(Object o)
+    public boolean equals(final Object o)
     {
         if (this == o)
         {
@@ -52,7 +52,7 @@ public class QuestSource implements SourceDataset
         {
             return false;
         }
-        QuestSource that = (QuestSource) o;
+        final QuestSource that = (QuestSource) o;
         return questId == that.questId;
     }
 
@@ -69,7 +69,7 @@ public class QuestSource implements SourceDataset
         {
             return String.format("Quest { %d, %s, %s..., %d }", this.questId, this.name, this.dialogue.getSubString(1, 10), this.personId);
         }
-        catch (SQLException e)
+        catch (final SQLException e)
         {
             e.printStackTrace();
         }
diff --git a/src/main/java/data/source/RelationshipsSource.java b/src/main/java/data/source/RelationshipsSource.java
index f2a6e9d..93563c6 100644
--- a/src/main/java/data/source/RelationshipsSource.java
+++ b/src/main/java/data/source/RelationshipsSource.java
@@ -4,10 +4,10 @@ import data.SourceDataset;
 
 public class RelationshipsSource implements SourceDataset
 {
-    private int personId;
-    private int relationshipLevel;
+    private final int personId;
+    private final int relationshipLevel;
 
-    public RelationshipsSource(int personId, int relationshipLevel)
+    public RelationshipsSource(final int personId, final int relationshipLevel)
     {
         this.personId = personId;
         this.relationshipLevel = relationshipLevel;
diff --git a/src/main/java/data/target/AbilityTarget.java b/src/main/java/data/target/AbilityTarget.java
index 0ee02fe..2eec3ae 100644
--- a/src/main/java/data/target/AbilityTarget.java
+++ b/src/main/java/data/target/AbilityTarget.java
@@ -4,12 +4,12 @@ import data.TargetDataset;
 
 public class AbilityTarget implements TargetDataset
 {
-    private int abilityId;
-    private String abilityName;
-    private String abilityDescription;
-    private float abilityLevel;
+    private final int abilityId;
+    private final String abilityName;
+    private final String abilityDescription;
+    private final float abilityLevel;
 
-    public AbilityTarget(int abilityId, String abilityName, String abilityDescription, float abilityLevel)
+    public AbilityTarget(final int abilityId, final String abilityName, final String abilityDescription, final float abilityLevel)
     {
         this.abilityId = abilityId;
         this.abilityName = abilityName;
diff --git a/src/main/java/data/target/ActiveQuestsTarget.java b/src/main/java/data/target/ActiveQuestsTarget.java
index 37048a3..4691fc1 100644
--- a/src/main/java/data/target/ActiveQuestsTarget.java
+++ b/src/main/java/data/target/ActiveQuestsTarget.java
@@ -4,11 +4,11 @@ import data.TargetDataset;
 
 public class ActiveQuestsTarget implements TargetDataset
 {
-    private int playerId;
-    private int questId;
-    private int questProgress;
+    private final int playerId;
+    private final int questId;
+    private final int questProgress;
 
-    public ActiveQuestsTarget(int playerId, int questId, int questProgress)
+    public ActiveQuestsTarget(final int playerId, final int questId, final int questProgress)
     {
         this.playerId = playerId;
         this.questId = questId;
diff --git a/src/main/java/data/target/CharacterInventoryTarget.java b/src/main/java/data/target/CharacterInventoryTarget.java
index 57dcc34..6e5c86d 100644
--- a/src/main/java/data/target/CharacterInventoryTarget.java
+++ b/src/main/java/data/target/CharacterInventoryTarget.java
@@ -4,10 +4,10 @@ import data.TargetDataset;
 
 public class CharacterInventoryTarget implements TargetDataset
 {
-    private int personId;
-    private int objectId;
+    private final int personId;
+    private final int objectId;
 
-    public CharacterInventoryTarget(int personId, int objectId)
+    public CharacterInventoryTarget(final int personId, final int objectId)
     {
         this.personId = personId;
         this.objectId = objectId;
diff --git a/src/main/java/data/target/CharacterTarget.java b/src/main/java/data/target/CharacterTarget.java
index bc7c8fa..3c9b2dd 100644
--- a/src/main/java/data/target/CharacterTarget.java
+++ b/src/main/java/data/target/CharacterTarget.java
@@ -1,15 +1,14 @@
 package data.target;
 
-import data.SourceDataset;
 import data.TargetDataset;
 
 public class CharacterTarget implements TargetDataset
 {
-    private int personId;
-    private String name;
-    private boolean mortal;
+    private final int personId;
+    private final String name;
+    private final boolean mortal;
 
-    public CharacterTarget(int personId, String name, boolean mortal)
+    public CharacterTarget(final int personId, final String name, final boolean mortal)
     {
         this.personId = personId;
         this.name = name;
diff --git a/src/main/java/data/target/GameobjectTarget.java b/src/main/java/data/target/GameobjectTarget.java
index 13813d3..c4e3b65 100644
--- a/src/main/java/data/target/GameobjectTarget.java
+++ b/src/main/java/data/target/GameobjectTarget.java
@@ -4,11 +4,11 @@ import data.TargetDataset;
 
 public class GameobjectTarget implements TargetDataset
 {
-    private int objectId;
-    private String name;
-    private String description;
+    private final int objectId;
+    private final String name;
+    private final String description;
 
-    public GameobjectTarget(int objectId, String name, String description)
+    public GameobjectTarget(final int objectId, final String name, final String description)
     {
         this.objectId = objectId;
         this.name = name;
diff --git a/src/main/java/data/target/InventoryTarget.java b/src/main/java/data/target/InventoryTarget.java
index 3a4fe0b..6a126d7 100644
--- a/src/main/java/data/target/InventoryTarget.java
+++ b/src/main/java/data/target/InventoryTarget.java
@@ -4,11 +4,11 @@ import data.TargetDataset;
 
 public class InventoryTarget implements TargetDataset
 {
-    private int playerId;
-    private int objectId;
-    private boolean stolen;
+    private final int playerId;
+    private final int objectId;
+    private final boolean stolen;
 
-    public InventoryTarget(int playerId, int objectId, boolean stolen)
+    public InventoryTarget(final int playerId, final int objectId, final boolean stolen)
     {
         this.playerId = playerId;
         this.objectId = objectId;
diff --git a/src/main/java/data/target/ModTarget.java b/src/main/java/data/target/ModTarget.java
index 5446599..a867b31 100644
--- a/src/main/java/data/target/ModTarget.java
+++ b/src/main/java/data/target/ModTarget.java
@@ -7,12 +7,12 @@ import java.time.LocalDate;
 
 public class ModTarget implements TargetDataset
 {
-    private int modId;
-    private String modName;
-    private LocalDate modInstallationDate;
-    private Blob modBinary;
+    private final int modId;
+    private final String modName;
+    private final LocalDate modInstallationDate;
+    private final Blob modBinary;
 
-    public ModTarget(int modId, String modName, LocalDate modInstallationDate, Blob modBinary)
+    public ModTarget(final int modId, final String modName, final LocalDate modInstallationDate, final Blob modBinary)
     {
         this.modId = modId;
         this.modName = modName;
diff --git a/src/main/java/data/target/PlayerAbilitiesTarget.java b/src/main/java/data/target/PlayerAbilitiesTarget.java
index 367fa15..5227850 100644
--- a/src/main/java/data/target/PlayerAbilitiesTarget.java
+++ b/src/main/java/data/target/PlayerAbilitiesTarget.java
@@ -4,10 +4,10 @@ import data.TargetDataset;
 
 public class PlayerAbilitiesTarget implements TargetDataset
 {
-    private int playerId;
-    private int abilityId;
+    private final int playerId;
+    private final int abilityId;
 
-    public PlayerAbilitiesTarget(int playerId, int abilityId)
+    public PlayerAbilitiesTarget(final int playerId, final int abilityId)
     {
         this.playerId = playerId;
         this.abilityId = abilityId;
diff --git a/src/main/java/data/target/PlayerTarget.java b/src/main/java/data/target/PlayerTarget.java
index ef1e4cd..c2f646c 100644
--- a/src/main/java/data/target/PlayerTarget.java
+++ b/src/main/java/data/target/PlayerTarget.java
@@ -4,10 +4,10 @@ import data.TargetDataset;
 
 public class PlayerTarget implements TargetDataset
 {
-    private int playerId;
-    private String playerName;
+    private final int playerId;
+    private final String playerName;
 
-    public PlayerTarget(int playerId, String playerName)
+    public PlayerTarget(final int playerId, final String playerName)
     {
         this.playerId = playerId;
         this.playerName = playerName;
diff --git a/src/main/java/data/target/QuestTarget.java b/src/main/java/data/target/QuestTarget.java
index d0bcacb..408c4af 100644
--- a/src/main/java/data/target/QuestTarget.java
+++ b/src/main/java/data/target/QuestTarget.java
@@ -7,12 +7,12 @@ import java.sql.SQLException;
 
 public class QuestTarget implements TargetDataset
 {
-    private int questId;
-    private String name;
-    private String involvedCharacters;
-    private Clob dialogue;
+    private final int questId;
+    private final String name;
+    private final String involvedCharacters;
+    private final Clob dialogue;
 
-    public QuestTarget(int questId, String name, String involvedCharacters, Clob dialogue)
+    public QuestTarget(final int questId, final String name, final String involvedCharacters, final Clob dialogue)
     {
         this.questId = questId;
         this.name = name;
@@ -47,7 +47,7 @@ public class QuestTarget implements TargetDataset
         {
             return String.format("Quest [ %d, %s, { %s }, %s... ]", this.questId, this.name, this.involvedCharacters, this.dialogue.getSubString(1, 10));
         }
-        catch (SQLException e)
+        catch (final SQLException e)
         {
             e.printStackTrace();
         }
diff --git a/src/main/java/data/target/RelationshipTarget.java b/src/main/java/data/target/RelationshipTarget.java
index e0450cb..2182f03 100644
--- a/src/main/java/data/target/RelationshipTarget.java
+++ b/src/main/java/data/target/RelationshipTarget.java
@@ -4,11 +4,11 @@ import data.TargetDataset;
 
 public class RelationshipTarget implements TargetDataset
 {
-    private int playerId;
-    private int personId;
-    private int relationshipLevel;
+    private final int playerId;
+    private final int personId;
+    private final int relationshipLevel;
 
-    public RelationshipTarget(int playerId, int personId, int relationshipLevel)
+    public RelationshipTarget(final int playerId, final int personId, final int relationshipLevel)
     {
         this.playerId = playerId;
         this.personId = personId;
diff --git a/src/main/java/etl/Extractor.java b/src/main/java/etl/Extractor.java
index dcb4a7d..14feeec 100644
--- a/src/main/java/etl/Extractor.java
+++ b/src/main/java/etl/Extractor.java
@@ -11,15 +11,15 @@ import java.util.List;
 
 public class Extractor<T extends SourceDataset>
 {
-    private static Logger log = Logger.getLogger(Extractor.class.getName());
+    private static final Logger log = Logger.getLogger(Extractor.class.getName());
 
-    private Connection sourceDatabase;
-    private DataStorer<T> dataStorer;
-    private StatementPreparerExtractor statementPreparer;
-    private String sql;
+    private final Connection sourceDatabase;
+    private final DataStorer<T> dataStorer;
+    private final StatementPreparerExtractor statementPreparer;
+    private final String sql;
 
-    public Extractor(Connection sourceDatabase, DataStorer<T> dataStorer,
-                     StatementPreparerExtractor statementPreparer, String sql)
+    public Extractor(final Connection sourceDatabase, final DataStorer<T> dataStorer,
+                     final StatementPreparerExtractor statementPreparer, final String sql)
     {
         this.sourceDatabase = sourceDatabase;
         this.dataStorer = dataStorer;
@@ -31,13 +31,13 @@ public class Extractor<T extends SourceDataset>
     {
         try
         {
-            var preparedStatement = this.sourceDatabase.prepareStatement(sql);
+            final var preparedStatement = this.sourceDatabase.prepareStatement(sql);
             this.statementPreparer.doPrepare(preparedStatement);
-            var resultSet = preparedStatement.executeQuery();
+            final var resultSet = preparedStatement.executeQuery();
             log.info(String.format("--- Data extracted with '%s' ---", this.sql));
             return this.dataStorer.doStore(resultSet);
         }
-        catch (SQLException e)
+        catch (final SQLException e)
         {
             e.printStackTrace();
         }
diff --git a/src/main/java/etl/Loader.java b/src/main/java/etl/Loader.java
index 65c449d..aad1769 100644
--- a/src/main/java/etl/Loader.java
+++ b/src/main/java/etl/Loader.java
@@ -1,6 +1,5 @@
 package etl;
 
-import data.SourceDataset;
 import data.TargetDataset;
 import org.apache.log4j.Logger;
 import utils.StatementPreparerLoader;
@@ -11,15 +10,15 @@ import java.util.List;
 
 public class Loader<T extends TargetDataset>
 {
-    private static Logger log = Logger.getLogger(Loader.class.getName());
+    private static final Logger log = Logger.getLogger(Loader.class.getName());
 
-    private Connection targetDatabase;
-    private StatementPreparerLoader<T> statementPreparerLoader;
-    private List<T> transformedData;
-    private String sql;
+    private final Connection targetDatabase;
+    private final StatementPreparerLoader<T> statementPreparerLoader;
+    private final List<T> transformedData;
+    private final String sql;
 
-    public Loader(Connection targetDatabase, StatementPreparerLoader<T> statementPreparerLoader, List<T> transformedData,
-                  String sql)
+    public Loader(final Connection targetDatabase, final StatementPreparerLoader<T> statementPreparerLoader, final List<T> transformedData,
+                  final String sql)
     {
         this.targetDatabase = targetDatabase;
         this.statementPreparerLoader = statementPreparerLoader;
@@ -31,16 +30,16 @@ public class Loader<T extends TargetDataset>
     {
         try
         {
-            for (T transformedDatum : this.transformedData)
+            for (final T transformedDatum : this.transformedData)
             {
                 log.info(String.format("Load data into target: %s", transformedDatum));
-                var preparedStatement = this.targetDatabase.prepareStatement(this.sql);
+                final var preparedStatement = this.targetDatabase.prepareStatement(this.sql);
                 this.statementPreparerLoader.doPrepare(preparedStatement, transformedDatum);
                 preparedStatement.executeUpdate();
             }
             log.info(String.format("--- Data loaded into target with '%s' ---", this.sql));
         }
-        catch (SQLException e)
+        catch (final SQLException e)
         {
             e.printStackTrace();
         }
diff --git a/src/main/java/etl/Transformer.java b/src/main/java/etl/Transformer.java
index fef0322..0c13acb 100644
--- a/src/main/java/etl/Transformer.java
+++ b/src/main/java/etl/Transformer.java
@@ -10,12 +10,12 @@ import java.util.List;
 
 public class Transformer<T extends SourceDataset, E extends TargetDataset>
 {
-    private static Logger log = Logger.getLogger(Transformer.class.getName());
+    private static final Logger log = Logger.getLogger(Transformer.class.getName());
 
-    private DataTransformer<T, E> transformer;
-    private List<T> extractedData;
+    private final DataTransformer<T, E> transformer;
+    private final List<T> extractedData;
 
-    public Transformer(DataTransformer<T, E> transformer, List<T> extractedData)
+    public Transformer(final DataTransformer<T, E> transformer, final List<T> extractedData)
     {
         this.transformer = transformer;
         this.extractedData = extractedData;
@@ -23,8 +23,8 @@ public class Transformer<T extends SourceDataset, E extends TargetDataset>
 
     public List<E> doTransform()
     {
-        var transformed = new ArrayList<E>();
-        for (T dataset : this.extractedData)
+        final var transformed = new ArrayList<E>();
+        for (final T dataset : this.extractedData)
         {
             log.info(String.format("Transform data: %s", dataset));
             transformed.add(this.transformer.transform(dataset));
diff --git a/src/main/java/migration/AbilityMigration.java b/src/main/java/migration/AbilityMigration.java
index 96ce99d..7797ab8 100644
--- a/src/main/java/migration/AbilityMigration.java
+++ b/src/main/java/migration/AbilityMigration.java
@@ -2,9 +2,7 @@ package migration;
 
 import com.mysql.cj.exceptions.NumberOutOfRange;
 import data.source.AbilitiesSource;
-import data.source.PersonSource;
 import data.target.AbilityTarget;
-import data.target.CharacterTarget;
 import etl.Extractor;
 import etl.Loader;
 import etl.Transformer;
@@ -18,7 +16,7 @@ public class AbilityMigration extends ETL<AbilitiesSource, AbilityTarget>
 {
     private int abilityId;
 
-    public AbilityMigration(Connection source, Connection target)
+    public AbilityMigration(final Connection source, final Connection target)
     {
         super(source, target);
         this.abilityId = 0;
@@ -27,8 +25,8 @@ public class AbilityMigration extends ETL<AbilitiesSource, AbilityTarget>
     @Override
     protected List<AbilitiesSource> extract()
     {
-        DataStorer<AbilitiesSource> dataStorer = (resultSet) -> {
-            var extractedData = new ArrayList<AbilitiesSource>();
+        final DataStorer<AbilitiesSource> dataStorer = (resultSet) -> {
+            final var extractedData = new ArrayList<AbilitiesSource>();
             while (resultSet.next())
             {
                 extractedData.add(new AbilitiesSource(
@@ -40,20 +38,20 @@ public class AbilityMigration extends ETL<AbilitiesSource, AbilityTarget>
             return extractedData;
         };
 
-        var sql = "select * from abilities;";
-        StatementPreparerExtractor statementPreparer = (preparedStatement) -> {};
+        final var sql = "select * from abilities;";
+        final StatementPreparerExtractor statementPreparer = (preparedStatement) -> {};
 
         return new Extractor<>(super.source, dataStorer, statementPreparer, sql).doExtract();
     }
 
     @Override
-    protected List<AbilityTarget> transform(List<AbilitiesSource> extractedData)
+    protected List<AbilityTarget> transform(final List<AbilitiesSource> extractedData)
     {
-        DataTransformer<AbilitiesSource, AbilityTarget> transformer = (dataset) -> {
+        final DataTransformer<AbilitiesSource, AbilityTarget> transformer = (dataset) -> {
             if (dataset.getLevel() < 0 || dataset.getLevel() > 100)
                 log.error("level-value out of range",
                         new NumberOutOfRange("level must be within 0 an 100 (both inclusive)"));
-            var levelCorrection = 100f;
+            final var levelCorrection = 100f;
             return new AbilityTarget(
                     abilityId++,
                     dataset.getName(),
@@ -66,16 +64,16 @@ public class AbilityMigration extends ETL<AbilitiesSource, AbilityTarget>
     }
 
     @Override
-    protected void load(List<AbilityTarget> transformedData)
+    protected void load(final List<AbilityTarget> transformedData)
     {
-        StatementPreparerLoader<AbilityTarget> statementPreparerLoader =  (preparedStatement, data) -> {
+        final StatementPreparerLoader<AbilityTarget> statementPreparerLoader =  (preparedStatement, data) -> {
             preparedStatement.setInt(1, data.getAbilityId());
             preparedStatement.setString(2, data.getAbilityName());
             preparedStatement.setString(3, data.getAbilityDescription());
             preparedStatement.setFloat(4, data.getAbilityLevel());
         };
 
-        var sql = "insert into ability values (?, ?, ?, ?)";
+        final var sql = "insert into ability values (?, ?, ?, ?)";
 
         new Loader<>(super.target, statementPreparerLoader, transformedData, sql).doLoad();
     }
diff --git a/src/main/java/migration/CharacterMigration.java b/src/main/java/migration/CharacterMigration.java
index bc11304..1a71caf 100644
--- a/src/main/java/migration/CharacterMigration.java
+++ b/src/main/java/migration/CharacterMigration.java
@@ -1,8 +1,6 @@
 package migration;
 
-import data.source.AbilitiesSource;
 import data.source.PersonSource;
-import data.target.AbilityTarget;
 import data.target.CharacterTarget;
 import etl.Extractor;
 import etl.Loader;
@@ -18,7 +16,7 @@ import java.util.List;
 
 public class CharacterMigration extends ETL<PersonSource, CharacterTarget>
 {
-    public CharacterMigration(Connection source, Connection target)
+    public CharacterMigration(final Connection source, final Connection target)
     {
         super(source, target);
     }
@@ -26,8 +24,8 @@ public class CharacterMigration extends ETL<PersonSource, CharacterTarget>
     @Override
     protected List<PersonSource> extract()
     {
-        DataStorer<PersonSource> dataStorer = (resultSet) -> {
-            var extractedData = new ArrayList<PersonSource>();
+        final DataStorer<PersonSource> dataStorer = (resultSet) -> {
+            final var extractedData = new ArrayList<PersonSource>();
             while (resultSet.next())
             {
                 extractedData.add(new PersonSource(
@@ -39,16 +37,16 @@ public class CharacterMigration extends ETL<PersonSource, CharacterTarget>
             return extractedData;
         };
 
-        var sql = "select * from person;";
-        StatementPreparerExtractor statementPreparer = (preparedStatement) -> {};
+        final var sql = "select * from person;";
+        final StatementPreparerExtractor statementPreparer = (preparedStatement) -> {};
 
         return new Extractor<>(super.source, dataStorer, statementPreparer, sql).doExtract();
     }
 
     @Override
-    protected List<CharacterTarget> transform(List<PersonSource> extractedData)
+    protected List<CharacterTarget> transform(final List<PersonSource> extractedData)
     {
-        DataTransformer<PersonSource, CharacterTarget> transformer =
+        final DataTransformer<PersonSource, CharacterTarget> transformer =
                 (dataset) -> new CharacterTarget(
                         dataset.getPersonId(),
                         dataset.getName(),
@@ -59,15 +57,15 @@ public class CharacterMigration extends ETL<PersonSource, CharacterTarget>
     }
 
     @Override
-    protected void load(List<CharacterTarget> transformedData)
+    protected void load(final List<CharacterTarget> transformedData)
     {
-        StatementPreparerLoader<CharacterTarget> statementPreparerLoader =  (preparedStatement, data) -> {
+        final StatementPreparerLoader<CharacterTarget> statementPreparerLoader =  (preparedStatement, data) -> {
             preparedStatement.setInt(1, data.getPersonId());
             preparedStatement.setString(2, data.getName());
             preparedStatement.setBoolean(3, data.isMortal());
         };
 
-        var sql = "insert into character values (?, ?, ?)";
+        final var sql = "insert into character values (?, ?, ?)";
 
         new Loader<>(super.target, statementPreparerLoader, transformedData, sql).doLoad();
     }
diff --git a/src/main/java/migration/ETL.java b/src/main/java/migration/ETL.java
index bd7fce1..88933e6 100644
--- a/src/main/java/migration/ETL.java
+++ b/src/main/java/migration/ETL.java
@@ -2,7 +2,6 @@ package migration;
 
 import data.SourceDataset;
 import data.TargetDataset;
-import data.source.PersonSource;
 import org.apache.log4j.Logger;
 
 import java.sql.Connection;
@@ -11,12 +10,12 @@ import java.util.List;
 
 public abstract class ETL<T extends SourceDataset, E extends TargetDataset>
 {
-    protected static Logger log = Logger.getLogger(ETL.class.getName());
+    protected static final Logger log = Logger.getLogger(ETL.class.getName());
 
-    protected Connection source;
-    protected Connection target;
+    protected final Connection source;
+    protected final Connection target;
 
-    public ETL(Connection source, Connection target)
+    public ETL(final Connection source, final Connection target)
     {
         this.source = source;
         this.target = target;
@@ -25,15 +24,15 @@ public abstract class ETL<T extends SourceDataset, E extends TargetDataset>
     public void migrate()
     {
         log.info(String.format("--- Migration: %s ---", this.getClass().getName()));
-        var extractedData = this.extract();
-        var transformedData = this.transform(extractedData);
+        final var extractedData = this.extract();
+        final var transformedData = this.transform(extractedData);
         this.load(transformedData);
 
         try
         {
             this.target.commit();
         }
-        catch (SQLException e)
+        catch (final SQLException e)
         {
             e.printStackTrace();
         }
diff --git a/src/main/java/migration/GameobjectMigration.java b/src/main/java/migration/GameobjectMigration.java
index f225381..2100a96 100644
--- a/src/main/java/migration/GameobjectMigration.java
+++ b/src/main/java/migration/GameobjectMigration.java
@@ -1,9 +1,6 @@
 package migration;
 
-import com.mysql.cj.exceptions.NumberOutOfRange;
-import data.source.AbilitiesSource;
 import data.source.GameobjectSource;
-import data.target.AbilityTarget;
 import data.target.GameobjectTarget;
 import etl.Extractor;
 import etl.Loader;
@@ -19,7 +16,7 @@ import java.util.List;
 
 public class GameobjectMigration extends ETL<GameobjectSource, GameobjectTarget>
 {
-    public GameobjectMigration(Connection source, Connection target)
+    public GameobjectMigration(final Connection source, final Connection target)
     {
         super(source, target);
     }
@@ -27,8 +24,8 @@ public class GameobjectMigration extends ETL<GameobjectSource, GameobjectTarget>
     @Override
     protected List<GameobjectSource> extract()
     {
-        DataStorer<GameobjectSource> dataStorer = (resultSet) -> {
-            var extractedData = new ArrayList<GameobjectSource>();
+        final DataStorer<GameobjectSource> dataStorer = (resultSet) -> {
+            final var extractedData = new ArrayList<GameobjectSource>();
             while (resultSet.next())
             {
                 extractedData.add(new GameobjectSource(
@@ -40,16 +37,16 @@ public class GameobjectMigration extends ETL<GameobjectSource, GameobjectTarget>
             return extractedData;
         };
 
-        var sql = "select * from gameobject;";
-        StatementPreparerExtractor statementPreparer = (preparedStatement) -> {};
+        final var sql = "select * from gameobject;";
+        final StatementPreparerExtractor statementPreparer = (preparedStatement) -> {};
 
         return new Extractor<>(super.source, dataStorer, statementPreparer, sql).doExtract();
     }
 
     @Override
-    protected List<GameobjectTarget> transform(List<GameobjectSource> extractedData)
+    protected List<GameobjectTarget> transform(final List<GameobjectSource> extractedData)
     {
-        DataTransformer<GameobjectSource, GameobjectTarget> transformer = (dataset) -> new GameobjectTarget(
+        final DataTransformer<GameobjectSource, GameobjectTarget> transformer = (dataset) -> new GameobjectTarget(
                 dataset.getObjectId(),
                 dataset.getName(),
                 dataset.getDescription()
@@ -59,15 +56,15 @@ public class GameobjectMigration extends ETL<GameobjectSource, GameobjectTarget>
     }
 
     @Override
-    protected void load(List<GameobjectTarget> transformedData)
+    protected void load(final List<GameobjectTarget> transformedData)
     {
-        StatementPreparerLoader<GameobjectTarget> statementPreparerLoader =  (preparedStatement, data) -> {
+        final StatementPreparerLoader<GameobjectTarget> statementPreparerLoader =  (preparedStatement, data) -> {
             preparedStatement.setInt(1, data.getObjectId());
             preparedStatement.setString(2, data.getName());
             preparedStatement.setString(3, data.getDescription());
         };
 
-        var sql = "insert into gameobject values (?, ?, ?)";
+        final var sql = "insert into gameobject values (?, ?, ?)";
 
         new Loader<>(super.target, statementPreparerLoader, transformedData, sql).doLoad();
     }
diff --git a/src/main/java/migration/ModMigration.java b/src/main/java/migration/ModMigration.java
index e37d789..de062d5 100644
--- a/src/main/java/migration/ModMigration.java
+++ b/src/main/java/migration/ModMigration.java
@@ -1,8 +1,6 @@
 package migration;
 
-import data.source.GameobjectSource;
 import data.source.ModSource;
-import data.target.GameobjectTarget;
 import data.target.ModTarget;
 import etl.Extractor;
 import etl.Loader;
@@ -19,7 +17,7 @@ import java.util.List;
 
 public class ModMigration extends ETL<ModSource, ModTarget>
 {
-    public ModMigration(Connection source, Connection target)
+    public ModMigration(final Connection source, final Connection target)
     {
         super(source, target);
     }
@@ -27,8 +25,8 @@ public class ModMigration extends ETL<ModSource, ModTarget>
     @Override
     protected List<ModSource> extract()
     {
-        DataStorer<ModSource> dataStorer = (resultSet) -> {
-            var extractedData = new ArrayList<ModSource>();
+        final DataStorer<ModSource> dataStorer = (resultSet) -> {
+            final var extractedData = new ArrayList<ModSource>();
             while (resultSet.next())
             {
                 extractedData.add(new ModSource(
@@ -41,16 +39,16 @@ public class ModMigration extends ETL<ModSource, ModTarget>
             return extractedData;
         };
 
-        var sql = "select * from `mod`;";
-        StatementPreparerExtractor statementPreparer = (preparedStatement) -> {};
+        final var sql = "select * from `mod`;";
+        final StatementPreparerExtractor statementPreparer = (preparedStatement) -> {};
 
         return new Extractor<>(super.source, dataStorer, statementPreparer, sql).doExtract();
     }
 
     @Override
-    protected List<ModTarget> transform(List<ModSource> extractedData)
+    protected List<ModTarget> transform(final List<ModSource> extractedData)
     {
-        DataTransformer<ModSource, ModTarget> transformer = (dataset) -> new ModTarget(
+        final DataTransformer<ModSource, ModTarget> transformer = (dataset) -> new ModTarget(
                 dataset.getModId(),
                 dataset.getName(),
                 dataset.getInstallationDate(),
@@ -61,16 +59,16 @@ public class ModMigration extends ETL<ModSource, ModTarget>
     }
 
     @Override
-    protected void load(List<ModTarget> transformedData)
+    protected void load(final List<ModTarget> transformedData)
     {
-        StatementPreparerLoader<ModTarget> statementPreparerLoader =  (preparedStatement, data) -> {
+        final StatementPreparerLoader<ModTarget> statementPreparerLoader =  (preparedStatement, data) -> {
             preparedStatement.setInt(1, data.getModId());
             preparedStatement.setString(2, data.getName());
             preparedStatement.setDate(3, Date.valueOf(data.getModInstallationDate()));
             preparedStatement.setBinaryStream(4, data.getModBinary().getBinaryStream());
         };
 
-        var sql = "insert into \"mod\" values (?, ?, ?, ?)";
+        final var sql = "insert into \"mod\" values (?, ?, ?, ?)";
 
         new Loader<>(super.target, statementPreparerLoader, transformedData, sql).doLoad();
     }
diff --git a/src/main/java/migration/PlayerAbilitiesMigration.java b/src/main/java/migration/PlayerAbilitiesMigration.java
index 8337d1e..525e95a 100644
--- a/src/main/java/migration/PlayerAbilitiesMigration.java
+++ b/src/main/java/migration/PlayerAbilitiesMigration.java
@@ -1,9 +1,6 @@
 package migration;
 
-import data.SourceDataset;
-import data.source.AbilitiesSource;
 import data.source.PlayerAbilitiesSource;
-import data.target.AbilityTarget;
 import data.target.PlayerAbilitiesTarget;
 import etl.Extractor;
 import etl.Loader;
@@ -19,7 +16,7 @@ import java.util.List;
 
 public class PlayerAbilitiesMigration extends ETL<PlayerAbilitiesSource, PlayerAbilitiesTarget>
 {
-    public PlayerAbilitiesMigration(Connection source, Connection target)
+    public PlayerAbilitiesMigration(final Connection source, final Connection target)
     {
         super(source, target);
     }
@@ -27,8 +24,8 @@ public class PlayerAbilitiesMigration extends ETL<PlayerAbilitiesSource, PlayerA
     @Override
     protected List<PlayerAbilitiesSource> extract()
     {
-        DataStorer<PlayerAbilitiesSource> dataStorer = (resultSet) -> {
-            var extractedData = new ArrayList<PlayerAbilitiesSource>();
+        final DataStorer<PlayerAbilitiesSource> dataStorer = (resultSet) -> {
+            final var extractedData = new ArrayList<PlayerAbilitiesSource>();
             while (resultSet.next())
             {
                 extractedData.add(new PlayerAbilitiesSource(
@@ -39,33 +36,31 @@ public class PlayerAbilitiesMigration extends ETL<PlayerAbilitiesSource, PlayerA
             return extractedData;
         };
 
-        var sql = "select * from player p join ability a on p.playerId = ?;";
-        StatementPreparerExtractor statementPreparer = (preparedStatement) -> {
-            preparedStatement.setInt(1, 0);
-        };
+        final var sql = "select * from player p join ability a on p.playerId = ?;";
+        final StatementPreparerExtractor statementPreparer = (preparedStatement) -> preparedStatement.setInt(1, 0);
 
         return new Extractor<>(super.source, dataStorer, statementPreparer, sql).doExtract();
     }
 
     @Override
-    protected List<PlayerAbilitiesTarget> transform(List<PlayerAbilitiesSource> extractedData)
+    protected List<PlayerAbilitiesTarget> transform(final List<PlayerAbilitiesSource> extractedData)
     {
-        DataTransformer<PlayerAbilitiesSource, PlayerAbilitiesTarget> transformer =
+        final DataTransformer<PlayerAbilitiesSource, PlayerAbilitiesTarget> transformer =
                 (dataset) -> new PlayerAbilitiesTarget(dataset.getPlayerId(), dataset.getAbilityId());
 
         return new Transformer<>(transformer, extractedData).doTransform();
     }
 
     @Override
-    protected void load(List<PlayerAbilitiesTarget> transformedData)
+    protected void load(final List<PlayerAbilitiesTarget> transformedData)
     {
 
-        StatementPreparerLoader<PlayerAbilitiesTarget> statementPreparerLoader =  (preparedStatement, data) -> {
+        final StatementPreparerLoader<PlayerAbilitiesTarget> statementPreparerLoader =  (preparedStatement, data) -> {
             preparedStatement.setInt(1, data.getPlayerId());
             preparedStatement.setInt(2, data.getAbilityId());
         };
 
-        var sql = "insert into playerAbilities values (?, ?)";
+        final var sql = "insert into playerAbilities values (?, ?)";
 
         new Loader<>(super.target, statementPreparerLoader, transformedData, sql).doLoad();
     }
diff --git a/src/main/java/migration/PlayerMigration.java b/src/main/java/migration/PlayerMigration.java
index 708eb48..9a3e843 100644
--- a/src/main/java/migration/PlayerMigration.java
+++ b/src/main/java/migration/PlayerMigration.java
@@ -3,9 +3,6 @@ package migration;
 import data.SourceDataset;
 import data.target.PlayerTarget;
 import etl.Loader;
-import utils.ConnectionHelper;
-import utils.DatabaseInformation;
-import utils.DatabaseType;
 import utils.StatementPreparerLoader;
 
 import java.sql.Connection;
@@ -13,7 +10,7 @@ import java.util.List;
 
 public class PlayerMigration extends ETL<SourceDataset, PlayerTarget>
 {
-    public PlayerMigration(Connection source, Connection target)
+    public PlayerMigration(final Connection source, final Connection target)
     {
         super(source, target);
     }
@@ -31,26 +28,26 @@ public class PlayerMigration extends ETL<SourceDataset, PlayerTarget>
     }
 
     @Override
-    protected List<PlayerTarget> transform(List<SourceDataset> extractedData)
+    protected List<PlayerTarget> transform(final List<SourceDataset> extractedData)
     {
         return null;
     }
 
     @Override
-    protected void load(List<PlayerTarget> transformedData)
+    protected void load(final List<PlayerTarget> transformedData)
     {
     }
 
     private void createPlayer()
     {
-        var sql = "insert into player values (?, ?)";
+        final var sql = "insert into player values (?, ?)";
 
-        StatementPreparerLoader<PlayerTarget> statementPreparerLoader =  (preparedStatement, data) -> {
+        final StatementPreparerLoader<PlayerTarget> statementPreparerLoader =  (preparedStatement, data) -> {
             preparedStatement.setInt(1, data.getPlayerId());
             preparedStatement.setString(2, data.getPlayerName());
         };
 
-        var transformedData = List.of(new PlayerTarget(0, "Dummy Name"));
+        final var transformedData = List.of(new PlayerTarget(0, "Dummy Name"));
 
         new Loader<>(this.target, statementPreparerLoader, transformedData, sql).doLoad();
     }
diff --git a/src/main/java/migration/QuestMigration.java b/src/main/java/migration/QuestMigration.java
index 9afc279..6235f14 100644
--- a/src/main/java/migration/QuestMigration.java
+++ b/src/main/java/migration/QuestMigration.java
@@ -18,7 +18,7 @@ import java.util.stream.Collectors;
 
 public class QuestMigration extends ETL<QuestSource, QuestTarget>
 {
-    public QuestMigration(Connection source, Connection target)
+    public QuestMigration(final Connection source, final Connection target)
     {
         super(source, target);
     }
@@ -26,8 +26,8 @@ public class QuestMigration extends ETL<QuestSource, QuestTarget>
     @Override
     protected List<QuestSource> extract()
     {
-        DataStorer<QuestSource> dataStorer = (resultSet) -> {
-            var extractedData = new ArrayList<QuestSource>();
+        final DataStorer<QuestSource> dataStorer = (resultSet) -> {
+            final var extractedData = new ArrayList<QuestSource>();
             while (resultSet.next())
             {
                 extractedData.add(new QuestSource(
@@ -39,8 +39,8 @@ public class QuestMigration extends ETL<QuestSource, QuestTarget>
             return extractedData;
         };
 
-        var sql = "select * from quest q join questParticipation qp on q.questId  = qp.questId;";
-        StatementPreparerExtractor statementPreparer = (preparedStatement) -> {};
+        final var sql = "select * from quest q join questParticipation qp on q.questId  = qp.questId;";
+        final StatementPreparerExtractor statementPreparer = (preparedStatement) -> {};
 
         return new Extractor<>(super.source, dataStorer, statementPreparer, sql).doExtract();
     }
@@ -48,25 +48,25 @@ public class QuestMigration extends ETL<QuestSource, QuestTarget>
     @Override
     protected List<QuestTarget> transform(List<QuestSource> extractedData)
     {
-        var map = new HashMap<Integer, String>();
+        final var map = new HashMap<Integer, String>();
 
-        for (QuestSource extractedDatum : extractedData)
+        for (final QuestSource extractedDatum : extractedData)
         {
-            var key = extractedDatum.getQuestId();
+            final var key = extractedDatum.getQuestId();
             if (!map.containsKey(key))
             {
                 map.put(key, String.valueOf(extractedDatum.getPersonId()));
             }
             else
             {
-                var involvedPersons = String.format("%s, %s", map.get(key), extractedDatum.getPersonId());
+                final var involvedPersons = String.format("%s, %s", map.get(key), extractedDatum.getPersonId());
                 map.replace(key, involvedPersons);
             }
         }
 
         extractedData = extractedData.stream().distinct().collect(Collectors.toList());
 
-        DataTransformer<QuestSource, QuestTarget> transformer = (dataset) -> new QuestTarget(
+        final DataTransformer<QuestSource, QuestTarget> transformer = (dataset) -> new QuestTarget(
                     dataset.getQuestId(),
                     dataset.getName(),
                     map.get(dataset.getQuestId()),
@@ -77,16 +77,16 @@ public class QuestMigration extends ETL<QuestSource, QuestTarget>
     }
 
     @Override
-    protected void load(List<QuestTarget> transformedData)
+    protected void load(final List<QuestTarget> transformedData)
     {
-        StatementPreparerLoader<QuestTarget> statementPreparerLoader =  (preparedStatement, data) -> {
+        final StatementPreparerLoader<QuestTarget> statementPreparerLoader =  (preparedStatement, data) -> {
             preparedStatement.setInt(1, data.getQuestId());
             preparedStatement.setString(2, data.getName());
             preparedStatement.setString(3, data.getInvolvedCharacters());
             preparedStatement.setClob(4, data.getDialogue());
         };
 
-        var sql = "insert into quest values (?, ?, ?, ?)";
+        final var sql = "insert into quest values (?, ?, ?, ?)";
 
         new Loader<>(super.target, statementPreparerLoader, transformedData, sql).doLoad();
     }
diff --git a/src/main/java/migration/ThesisMigration.java b/src/main/java/migration/ThesisMigration.java
index d87923c..6d0a6c5 100644
--- a/src/main/java/migration/ThesisMigration.java
+++ b/src/main/java/migration/ThesisMigration.java
@@ -10,15 +10,16 @@ import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;
 
+@SuppressWarnings("ALL")
 public class ThesisMigration
 {
-    private static Logger log = Logger.getLogger(ThesisMigration.class.getName());
+    private static final Logger log = Logger.getLogger(ThesisMigration.class.getName());
 
-    private List<ETL> migrations;
+    private final List<ETL> migrations;
 
-    private Connection mariadb;
-    private Connection mysql;
-    private Connection postgresql;
+    private final Connection mariadb;
+    private final Connection mysql;
+    private final Connection postgresql;
 
     public ThesisMigration()
     {
@@ -38,7 +39,7 @@ public class ThesisMigration
             this.mysql.setAutoCommit(false);
             this.postgresql.setAutoCommit(false);
         }
-        catch (SQLException e)
+        catch (final SQLException e)
         {
             e.printStackTrace();
         }
@@ -55,17 +56,23 @@ public class ThesisMigration
 
     public void executeMigrations()
     {
-        log.info("\n----- Starting migrations for each migration step -----\n");
+        log.info("""
+
+                ----- Starting migrations for each migration step -----
+                """);
         this.migrations.forEach(ETL::migrate);
 
         try
         {
-            log.info("\n--- Closing connections ---\n");
+            log.info("""
+
+                    --- Closing connections ---
+                    """);
             this.mariadb.close();
             this.mysql.close();
             this.postgresql.close();
         }
-        catch (SQLException e)
+        catch (final SQLException e)
         {
             e.printStackTrace();
         }
diff --git a/src/main/java/utils/ConnectionHelper.java b/src/main/java/utils/ConnectionHelper.java
index 81155d0..74edf00 100644
--- a/src/main/java/utils/ConnectionHelper.java
+++ b/src/main/java/utils/ConnectionHelper.java
@@ -1,6 +1,5 @@
 package utils;
 
-import migration.ThesisMigration;
 import org.apache.log4j.Logger;
 
 import java.net.URI;
@@ -9,7 +8,7 @@ import java.sql.*;
 
 public class ConnectionHelper
 {
-    private static Logger log = Logger.getLogger(ConnectionHelper.class.getName());
+    private static final Logger log = Logger.getLogger(ConnectionHelper.class.getName());
 
     private final DatabaseType databaseType;
     private final String user;
diff --git a/src/main/java/utils/DatabaseHelper.java b/src/main/java/utils/DatabaseHelper.java
deleted file mode 100644
index 80debfa..0000000
--- a/src/main/java/utils/DatabaseHelper.java
+++ /dev/null
@@ -1,5 +0,0 @@
-package utils;
-
-public class DatabaseHelper
-{
-}
diff --git a/src/main/java/utils/StatementPreparerLoader.java b/src/main/java/utils/StatementPreparerLoader.java
index b00e992..705827a 100644
--- a/src/main/java/utils/StatementPreparerLoader.java
+++ b/src/main/java/utils/StatementPreparerLoader.java
@@ -1,6 +1,5 @@
 package utils;
 
-import data.SourceDataset;
 import data.TargetDataset;
 
 import java.sql.PreparedStatement;