diff --git a/Mage.Client/src/main/java/org/mage/plugins/card/utils/CardImageUtils.java b/Mage.Client/src/main/java/org/mage/plugins/card/utils/CardImageUtils.java
index 759787d6186..74db210fe9e 100644
--- a/Mage.Client/src/main/java/org/mage/plugins/card/utils/CardImageUtils.java
+++ b/Mage.Client/src/main/java/org/mage/plugins/card/utils/CardImageUtils.java
@@ -3,6 +3,7 @@ package org.mage.plugins.card.utils;
 import java.net.InetSocketAddress;
 import java.net.Proxy;
 import java.util.HashMap;
+import java.util.Objects;
 import java.util.prefs.Preferences;
 import mage.client.MageFrame;
 import mage.client.constants.Constants;
@@ -120,8 +121,9 @@ public class CardImageUtils {
 
     public static String getImageBasePath() {
         String useDefault = PreferencesDialog.getCachedValue(PreferencesDialog.KEY_CARD_IMAGES_USE_DEFAULT, "true");
-        String imagesPath = useDefault.equals("true") ? Constants.IO.imageBaseDir : PreferencesDialog.getCachedValue(PreferencesDialog.KEY_CARD_IMAGES_PATH, null);
-        if (!imagesPath.endsWith(TFile.separator)) {
+        String imagesPath = Objects.equals(useDefault, "true") ? Constants.IO.imageBaseDir : PreferencesDialog.getCachedValue(PreferencesDialog.KEY_CARD_IMAGES_PATH, null);
+
+        if (imagesPath != null && !imagesPath.endsWith(TFile.separator)) {
             imagesPath += TFile.separator;
         }
         return imagesPath;
@@ -161,7 +163,7 @@ public class CardImageUtils {
 
     public static String generateImagePath(CardDownloadData card) {
         String useDefault = PreferencesDialog.getCachedValue(PreferencesDialog.KEY_CARD_IMAGES_USE_DEFAULT, "true");
-        String imagesPath = useDefault.equals("true") ? null : PreferencesDialog.getCachedValue(PreferencesDialog.KEY_CARD_IMAGES_PATH, null);
+        String imagesPath = Objects.equals(useDefault, "true") ? null : PreferencesDialog.getCachedValue(PreferencesDialog.KEY_CARD_IMAGES_PATH, null);
 
         String imageDir = getImageDir(card, imagesPath);
         String imageName;
@@ -189,7 +191,7 @@ public class CardImageUtils {
 
     public static String generateTokenDescriptorImagePath(CardDownloadData card) {
         String useDefault = PreferencesDialog.getCachedValue(PreferencesDialog.KEY_CARD_IMAGES_USE_DEFAULT, "true");
-        String imagesPath = useDefault.equals("true") ? null : PreferencesDialog.getCachedValue(PreferencesDialog.KEY_CARD_IMAGES_PATH, null);
+        String imagesPath = Objects.equals(useDefault, "true") ? null : PreferencesDialog.getCachedValue(PreferencesDialog.KEY_CARD_IMAGES_PATH, null);
 
         String straightImageFile = getTokenDescriptorImagePath(card);
         TFile file = new TFile(straightImageFile);
diff --git a/Mage/src/main/java/mage/cards/repository/ExpansionInfo.java b/Mage/src/main/java/mage/cards/repository/ExpansionInfo.java
index 4bff5ee0ca4..572e5ef3d19 100644
--- a/Mage/src/main/java/mage/cards/repository/ExpansionInfo.java
+++ b/Mage/src/main/java/mage/cards/repository/ExpansionInfo.java
@@ -16,7 +16,7 @@ public class ExpansionInfo {
 
     @DatabaseField(unique = true)
     protected String name;
-    @DatabaseField(unique = true)
+    @DatabaseField(id = true,unique = true)
     protected String code;
     @DatabaseField
     protected String blockName;
diff --git a/Mage/src/main/java/mage/target/TargetSpell.java b/Mage/src/main/java/mage/target/TargetSpell.java
index f679aadddc4..aad10b11ef8 100644
--- a/Mage/src/main/java/mage/target/TargetSpell.java
+++ b/Mage/src/main/java/mage/target/TargetSpell.java
@@ -132,6 +132,6 @@ public class TargetSpell extends TargetObject {
     private boolean canBeChosen(StackObject stackObject, UUID sourceID, UUID sourceControllerId, Game game) {
         return stackObject instanceof Spell
                 && game.getState().getPlayersInRange(sourceControllerId, game).contains(stackObject.getControllerId())
-                && filter.match((Spell) stackObject, sourceID, sourceControllerId, game);
+                && filter.match(stackObject, sourceID, sourceControllerId, game);
     }
 }
diff --git a/Mage/src/main/java/mage/target/common/TargetCardInLibrary.java b/Mage/src/main/java/mage/target/common/TargetCardInLibrary.java
index 699f7278b60..b23298e1074 100644
--- a/Mage/src/main/java/mage/target/common/TargetCardInLibrary.java
+++ b/Mage/src/main/java/mage/target/common/TargetCardInLibrary.java
@@ -28,7 +28,6 @@
 package mage.target.common;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.UUID;
diff --git a/Mage/src/main/java/mage/target/common/TargetOpponent.java b/Mage/src/main/java/mage/target/common/TargetOpponent.java
index 4483f1e971c..91d813c6c85 100644
--- a/Mage/src/main/java/mage/target/common/TargetOpponent.java
+++ b/Mage/src/main/java/mage/target/common/TargetOpponent.java
@@ -56,16 +56,6 @@ public class TargetOpponent extends TargetPlayer {
         super(target);
     }
 
-    @Override
-    public boolean canChoose(UUID sourceId, UUID sourceControllerId, Game game) {
-        return super.canChoose(sourceId, sourceControllerId, game);
-    }
-
-    @Override
-    public boolean canTarget(UUID id, Ability source, Game game) {
-        return super.canTarget(id, source, game);
-    }
-
     @Override
     public TargetOpponent copy() {
         return new TargetOpponent(this);
diff --git a/Mage/src/main/java/mage/util/CardUtil.java b/Mage/src/main/java/mage/util/CardUtil.java
index a007722f8fd..d40647ebae2 100644
--- a/Mage/src/main/java/mage/util/CardUtil.java
+++ b/Mage/src/main/java/mage/util/CardUtil.java
@@ -69,7 +69,7 @@ public class CardUtil {
 
     private static final String SOURCE_EXILE_ZONE_TEXT = "SourceExileZone";
 
-    static String numberStrings[] = {"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine",
+    static final String[] numberStrings = {"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine",
         "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "ninteen", "twenty"};
 
     public static final String[] NON_CHANGELING_SUBTYPES_VALUES = new String[]{
diff --git a/Mage/src/main/java/mage/util/CircularList.java b/Mage/src/main/java/mage/util/CircularList.java
index 27eaf144bfa..7a131d4d441 100644
--- a/Mage/src/main/java/mage/util/CircularList.java
+++ b/Mage/src/main/java/mage/util/CircularList.java
@@ -45,7 +45,7 @@ import java.util.concurrent.locks.ReentrantLock;
 public class CircularList<E> implements List<E>, Iterable<E>, Serializable {
     //TODO: might have to make E extend Copyable
 
-    protected List<E> list = new ArrayList<>();
+    protected final List<E> list = new ArrayList<>();
 
     protected final ReentrantLock lock = new ReentrantLock();
 
@@ -357,8 +357,8 @@ public class CircularList<E> implements List<E>, Iterable<E>, Serializable {
     private class CircularIterator<E> implements Iterator<E> {
 
         int cursor;
-        int lastIndex;
-        int curModCount;
+        final int lastIndex;
+        final int curModCount;
         boolean hasMoved = false;
 
         private CircularIterator() {
@@ -399,9 +399,9 @@ public class CircularList<E> implements List<E>, Iterable<E>, Serializable {
     private class CircularListIterator<E> implements ListIterator<E> {
 
         int cursor;
-        int lastIndex;
-        int firstIndex;
-        int curModCount;
+        final int lastIndex;
+        final int firstIndex;
+        final int curModCount;
         boolean hasMoved = false;
 
         private CircularListIterator() {
diff --git a/Mage/src/main/java/mage/util/CopierObjectInputStream.java b/Mage/src/main/java/mage/util/CopierObjectInputStream.java
index 72189f7b76a..cfde5cd1c17 100644
--- a/Mage/src/main/java/mage/util/CopierObjectInputStream.java
+++ b/Mage/src/main/java/mage/util/CopierObjectInputStream.java
@@ -32,7 +32,6 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.ObjectInputStream;
 import java.io.ObjectStreamClass;
-import java.io.StreamCorruptedException;
 
 /**
  *
diff --git a/Mage/src/main/java/mage/util/TargetAddress.java b/Mage/src/main/java/mage/util/TargetAddress.java
index 80c5724676d..0a0d1820575 100644
--- a/Mage/src/main/java/mage/util/TargetAddress.java
+++ b/Mage/src/main/java/mage/util/TargetAddress.java
@@ -42,9 +42,9 @@ import mage.target.Target;
  */
 public class TargetAddress {
 
-    protected int spellAbilityIndex;
-    protected UUID mode;
-    protected int targetIndex;
+    protected final int spellAbilityIndex;
+    protected final UUID mode;
+    protected final int targetIndex;
 
     public TargetAddress(int spellAbilityIndex, UUID mode, int targetIndex) {
         this.spellAbilityIndex = spellAbilityIndex;
@@ -68,7 +68,7 @@ public class TargetAddress {
 
     protected static class TargetAddressIterator implements Iterator<TargetAddress> {
 
-        protected Iterator<SpellAbility> spellAbilityIterator;
+        protected final Iterator<SpellAbility> spellAbilityIterator;
         protected Integer lastSpellAbilityIndex = null;
         protected Iterator<UUID> modeIterator = null;
         protected Modes modes = null;
diff --git a/Mage/src/main/java/mage/util/ThreadLocalStringBuilder.java b/Mage/src/main/java/mage/util/ThreadLocalStringBuilder.java
index bfa102d83f7..e27257936f8 100644
--- a/Mage/src/main/java/mage/util/ThreadLocalStringBuilder.java
+++ b/Mage/src/main/java/mage/util/ThreadLocalStringBuilder.java
@@ -6,7 +6,7 @@ package mage.util;
  */
 public class ThreadLocalStringBuilder extends ThreadLocal<StringBuilder> {
 
-    private int size;
+    private final int size;
     
     public ThreadLocalStringBuilder(int size) {
         this.size = size;
diff --git a/Mage/src/main/java/mage/watchers/Watchers.java b/Mage/src/main/java/mage/watchers/Watchers.java
index 70227e9d2d6..61c5b8ec264 100644
--- a/Mage/src/main/java/mage/watchers/Watchers.java
+++ b/Mage/src/main/java/mage/watchers/Watchers.java
@@ -28,7 +28,6 @@
 package mage.watchers;
 
 import java.util.HashMap;
-import java.util.Iterator;
 import java.util.UUID;
 import mage.game.Game;
 import mage.game.events.GameEvent;
@@ -43,7 +42,7 @@ public class Watchers extends HashMap<String, Watcher> {
     }
 
     public Watchers(final Watchers watchers) {
-        watchers.entrySet().stream().forEach((entry) -> this.put(entry.getKey(), entry.getValue().copy()));
+        watchers.entrySet().forEach((entry) -> this.put(entry.getKey(), entry.getValue().copy()));
     }
 
     public Watchers copy() {
@@ -63,7 +62,7 @@ public class Watchers extends HashMap<String, Watcher> {
     }
 
     public void reset() {
-        this.values().stream().forEach(Watcher::reset);
+        this.values().forEach(Watcher::reset);
     }
 
     public Watcher get(String key, UUID id) {
diff --git a/Mage/src/main/java/mage/watchers/common/CastFromGraveyardWatcher.java b/Mage/src/main/java/mage/watchers/common/CastFromGraveyardWatcher.java
index 41d07639af4..44e831b1f58 100644
--- a/Mage/src/main/java/mage/watchers/common/CastFromGraveyardWatcher.java
+++ b/Mage/src/main/java/mage/watchers/common/CastFromGraveyardWatcher.java
@@ -66,11 +66,7 @@ public class CastFromGraveyardWatcher extends Watcher {
         if (event.getType() == GameEvent.EventType.SPELL_CAST && event.getZone().equals(Zone.GRAVEYARD)) {
             Spell spell = (Spell) game.getObject(event.getTargetId());
             if (spell != null) {
-                HashSet<Integer> zcc = spellsCastFromGraveyard.get(spell.getSourceId());
-                if (zcc == null) {
-                    zcc = new HashSet<>();
-                    spellsCastFromGraveyard.put(spell.getSourceId(), zcc);
-                }
+                HashSet<Integer> zcc = spellsCastFromGraveyard.computeIfAbsent(spell.getSourceId(), k -> new HashSet<>());
                 zcc.add(spell.getZoneChangeCounter(game));
             }
 
diff --git a/Mage/src/main/java/mage/watchers/common/FirstTimeStepWatcher.java b/Mage/src/main/java/mage/watchers/common/FirstTimeStepWatcher.java
index d216f48d37a..303f4586a24 100644
--- a/Mage/src/main/java/mage/watchers/common/FirstTimeStepWatcher.java
+++ b/Mage/src/main/java/mage/watchers/common/FirstTimeStepWatcher.java
@@ -64,9 +64,4 @@ public class FirstTimeStepWatcher extends Watcher {
             condition = true;
         }
     }
-
-    @Override
-    public void reset() {
-        super.reset();
-    }
 }