diff --git a/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/DownloadListener.java b/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/DownloadListener.java
index 0f77fbc..78f3927 100644
--- a/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/DownloadListener.java
+++ b/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/DownloadListener.java
@@ -22,7 +22,7 @@ import org.openstreetmap.josm.tools.Destroyable;
  */
 public final class DownloadListener implements DataSourceListener, Destroyable {
 
-    private WeakReference<DataSet> ds;
+    private final WeakReference<DataSet> ds;
     private static final Collection<DownloadListener> LISTENERS = new HashSet<>();
 
     public DownloadListener(DataSet dataSet) {
diff --git a/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/MapWithAILayer.java b/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/MapWithAILayer.java
index 403fde7..5a03bc1 100644
--- a/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/MapWithAILayer.java
+++ b/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/MapWithAILayer.java
@@ -226,7 +226,7 @@ public class MapWithAILayer extends OsmDataLayer implements ActiveLayerChangeLis
         return continuousDownload;
     }
 
-    private class ContinuousDownloadAction extends AbstractAction implements LayerAction {
+    private static class ContinuousDownloadAction extends AbstractAction implements LayerAction {
         private static final long serialVersionUID = -3528632887550700527L;
         private final MapWithAILayer layer;
 
diff --git a/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/MapWithAIMoveAction.java b/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/MapWithAIMoveAction.java
index 8a20358..b93523d 100644
--- a/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/MapWithAIMoveAction.java
+++ b/src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/MapWithAIMoveAction.java
@@ -74,8 +74,8 @@ public class MapWithAIMoveAction extends JosmAction {
             }
             final Collection<OsmPrimitive> selected = limitCollection(ds, maxAddition);
             final OsmDataLayer editLayer = getOsmDataLayer();
-            if (editLayer != null && !selected.isEmpty()
-                    && (MapWithAIDataUtils.getAddedObjects() < maxAddition * MAX_ADD_MULTIPLIER)
+            if ((editLayer != null && !selected.isEmpty()
+                    && (MapWithAIDataUtils.getAddedObjects() < maxAddition * MAX_ADD_MULTIPLIER))
                     || (maxAddition == 0 && ExpertToggleAction.isExpert())) {
                 final MapWithAIAddCommand command = new MapWithAIAddCommand(mapWithAI, editLayer, selected);
                 UndoRedoHandler.getInstance().add(command);
@@ -88,7 +88,7 @@ public class MapWithAIMoveAction extends JosmAction {
         }
     }
 
-    private void createTooManyAdditionsNotification(int maxAddition) {
+    private static void createTooManyAdditionsNotification(int maxAddition) {
         Notification tooMany = new Notification();
         tooMany.setIcon(JOptionPane.WARNING_MESSAGE);
         tooMany.setDuration(Notification.TIME_DEFAULT);
diff --git a/src/main/java/org/openstreetmap/josm/plugins/mapwithai/data/validation/tests/RoutingIslandsTest.java b/src/main/java/org/openstreetmap/josm/plugins/mapwithai/data/validation/tests/RoutingIslandsTest.java
index 011b394..e9a0026 100644
--- a/src/main/java/org/openstreetmap/josm/plugins/mapwithai/data/validation/tests/RoutingIslandsTest.java
+++ b/src/main/java/org/openstreetmap/josm/plugins/mapwithai/data/validation/tests/RoutingIslandsTest.java
@@ -102,8 +102,8 @@ public class RoutingIslandsTest extends Test {
                 errors.add(TestError.builder(this, SEVERITY_MAP.get(LONELY_WAY), LONELY_WAY).primitives(way)
                         .message(tr("MapWithAI (experimental)"), marktr("Routable way not connected to other ways"))
                         .build());
-            } else if (((ValidatorPrefHelper.PREF_OTHER.get() || ValidatorPrefHelper.PREF_OTHER_UPLOAD.get()
-                    || !Severity.OTHER.equals(SEVERITY_MAP.get(ROUTING_ISLAND)))) && !isBeforeUpload) {
+            } else if ((ValidatorPrefHelper.PREF_OTHER.get() || ValidatorPrefHelper.PREF_OTHER_UPLOAD.get()
+                    || !Severity.OTHER.equals(SEVERITY_MAP.get(ROUTING_ISLAND))) && !isBeforeUpload) {
                 if (way.hasKey(HIGHWAY)) {
                     potentialHighways.add(way);
                 } else if (way.hasKey(WATERWAY)) {
@@ -395,7 +395,7 @@ public class RoutingIslandsTest extends Test {
      */
     public static Node firstNode(Way way, String transportType) {
         Integer oneway = isOneway(way, transportType);
-        Node node = (Integer.valueOf(-1).equals(oneway)) ? way.lastNode() : way.firstNode();
+        Node node = Integer.valueOf(-1).equals(oneway) ? way.lastNode() : way.firstNode();
 
         Map<String, String> accessValues = getDefaultAccessTags(way);
         boolean accessible = Access.getPositiveAccessValues()
@@ -413,7 +413,7 @@ public class RoutingIslandsTest extends Test {
      */
     public static Node lastNode(Way way, String transportType) {
         Integer oneway = isOneway(way, transportType);
-        Node node = (Integer.valueOf(-1).equals(oneway)) ? way.firstNode() : way.lastNode();
+        Node node = Integer.valueOf(-1).equals(oneway) ? way.firstNode() : way.lastNode();
         Map<String, String> accessValues = getDefaultAccessTags(way);
         boolean accessible = Access.getPositiveAccessValues()
                 .contains(accessValues.getOrDefault(transportType, Access.AccessTags.NO.getKey()));
diff --git a/src/main/java/org/openstreetmap/josm/plugins/mapwithai/tools/Access.java b/src/main/java/org/openstreetmap/josm/plugins/mapwithai/tools/Access.java
index d2e0e12..7ba2003 100644
--- a/src/main/java/org/openstreetmap/josm/plugins/mapwithai/tools/Access.java
+++ b/src/main/java/org/openstreetmap/josm/plugins/mapwithai/tools/Access.java
@@ -340,8 +340,8 @@ public class Access {
          */
         TRAIN("train", RAIL_TRANSPORT_TYPE);
 
-        private String key;
-        private AccessTags type;
+        private final String key;
+        private final AccessTags type;
 
         AccessTags(String key) {
             this.key = key;