Index: trunk/src/org/openstreetmap/josm/data/Preferences.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/Preferences.java	(revision 11460)
+++ trunk/src/org/openstreetmap/josm/data/Preferences.java	(revision 11461)
@@ -1584,5 +1584,5 @@
         if (setting instanceof MapListSetting) {
             List<Map<String, String>> l = new ArrayList<>(((MapListSetting) setting).getValue());
-            if (l.stream().noneMatch(x -> x.values().contains(url))) {
+            if (l.stream().noneMatch(x -> x.containsValue(url))) {
                 RulePrefHelper helper = ValidatorTagCheckerRulesPreference.RulePrefHelper.INSTANCE;
                 Optional<ExtendedSourceEntry> val = helper.getDefault().stream().filter(x -> url.equals(x.url)).findFirst();
Index: trunk/src/org/openstreetmap/josm/data/osm/visitor/MergeSourceBuildingVisitor.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/visitor/MergeSourceBuildingVisitor.java	(revision 11460)
+++ trunk/src/org/openstreetmap/josm/data/osm/visitor/MergeSourceBuildingVisitor.java	(revision 11461)
@@ -55,5 +55,5 @@
 
     protected boolean isAlreadyRemembered(OsmPrimitive primitive) {
-        return mappedPrimitives.keySet().contains(primitive);
+        return mappedPrimitives.containsKey(primitive);
     }
 
Index: trunk/src/org/openstreetmap/josm/data/preferences/MapListSetting.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/preferences/MapListSetting.java	(revision 11460)
+++ trunk/src/org/openstreetmap/josm/data/preferences/MapListSetting.java	(revision 11461)
@@ -41,7 +41,7 @@
             throw new IllegalArgumentException("Error: Null as list element in preference setting");
         for (Map<String, String> map : value) {
-            if (map.keySet().contains(null))
+            if (map.containsKey(null))
                 throw new IllegalArgumentException("Error: Null as map key in preference setting");
-            if (map.values().contains(null))
+            if (map.containsValue(null))
                 throw new IllegalArgumentException("Error: Null as map value in preference setting");
         }
Index: trunk/src/org/openstreetmap/josm/gui/dialogs/relation/RelationDialogManager.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/relation/RelationDialogManager.java	(revision 11460)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/relation/RelationDialogManager.java	(revision 11461)
@@ -150,6 +150,5 @@
         if (relation == null) return false;
         DialogContext context = new DialogContext(layer, relation);
-        return openDialogs.keySet().contains(context);
-
+        return openDialogs.containsKey(context);
     }
 
Index: trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserDialogManager.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserDialogManager.java	(revision 11460)
+++ trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserDialogManager.java	(revision 11461)
@@ -88,5 +88,5 @@
 
     private void show(long id, HistoryBrowserDialog dialog) {
-        if (dialogs.values().contains(dialog)) {
+        if (dialogs.containsValue(dialog)) {
             show(id);
         } else {
@@ -98,5 +98,5 @@
 
     private void show(long id) {
-        if (dialogs.keySet().contains(id)) {
+        if (dialogs.containsKey(id)) {
             dialogs.get(id).toFront();
         }