diff --git a/src/main/java/de/blau/android/Main.java b/src/main/java/de/blau/android/Main.java
index 030b2dc91..8cb4506f0 100644
--- a/src/main/java/de/blau/android/Main.java
+++ b/src/main/java/de/blau/android/Main.java
@@ -6,6 +6,7 @@
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Deque;
@@ -2818,7 +2819,7 @@ public void gotoTrackPoint(@NonNull final Logic logic, @NonNull TrackPoint track
     private File getImageFile() throws IOException {
         File outDir = FileUtil.getPublicDirectory(FileUtil.getPublicDirectory(), Paths.DIRECTORY_PATH_PICTURES);
         String imageFileName = DateFormatter.getFormattedString(DATE_PATTERN_IMAGE_FILE_NAME_PART);
-        //FIXME this forces the extension to jpg, but it could be a HEIC image 
+        // FIXME this forces the extension to jpg, but it could be a HEIC image
         File newImageFile = File.createTempFile(imageFileName, "." + FileExtensions.JPG, outDir);
         Log.d(DEBUG_TAG, "getImageFile " + newImageFile.getAbsolutePath());
         return newImageFile;
@@ -3332,8 +3333,8 @@ public void performTagEdit(@NonNull final OsmElement selectedElement, @Nullable
      * @param tags any existing tags to apply
      * @param showPresets show the preset tab on start up.
      */
-    public void performTagEdit(@NonNull final OsmElement selectedElement, @Nullable PresetElementPath presetPath, @Nullable HashMap<String, String> tags,
-            boolean showPresets) {
+    public <M extends java.util.Map<String, String> & Serializable> void performTagEdit(@NonNull final OsmElement selectedElement, @Nullable PresetElementPath presetPath,
+            @Nullable M tags, boolean showPresets) {
         ArrayList<PresetElementPath> presetPathList = new ArrayList<>();
         if (presetPath != null) {
             presetPathList.add(presetPath);
@@ -3351,8 +3352,9 @@ public void performTagEdit(@NonNull final OsmElement selectedElement, @Nullable
      * @param tags any existing tags to apply
      * @param showPresets show the preset tab on start up.
      */
-    private void performTagEdit(@NonNull final OsmElement selectedElement, @Nullable String focusOn, boolean applyLastAddressTags,
-            @Nullable ArrayList<PresetElementPath> presetPathList, @Nullable HashMap<String, String> tags, boolean showPresets) {
+    private <M extends java.util.Map<String, String> & Serializable, L extends List<PresetElementPath> & Serializable> void performTagEdit(
+            @NonNull final OsmElement selectedElement, @Nullable String focusOn, boolean applyLastAddressTags, @Nullable L presetPathList, @Nullable M tags,
+            boolean showPresets) {
         descheduleAutoLock();
         unlock();
         final Logic logic = App.getLogic();
diff --git a/src/main/java/de/blau/android/Mode.java b/src/main/java/de/blau/android/Mode.java
index b3ccb4724..fc77f5d8a 100644
--- a/src/main/java/de/blau/android/Mode.java
+++ b/src/main/java/de/blau/android/Mode.java
@@ -1,9 +1,12 @@
 package de.blau.android;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 import android.content.Context;
@@ -61,14 +64,16 @@ public void teardown(Main main, Logic logic) {
             // empty
         }
 
+        @SuppressWarnings("unchecked")
         @Override
-        public HashMap<String, String> getExtraTags(@NonNull Logic logic, @NonNull OsmElement e) {
-            return null;
+        public <M extends Map<String, String> & Serializable> M getExtraTags(@NonNull Logic logic, @NonNull OsmElement e) {
+            return (M) new HashMap<String, String>();
         }
 
+        @SuppressWarnings("unchecked")
         @Override
-        public ArrayList<PresetElementPath> getPresetItems(@NonNull Context ctx, @NonNull OsmElement e) {
-            return null;
+        public <L extends List<PresetElementPath> & Serializable> L getPresetItems(@NonNull Context ctx, @NonNull OsmElement e) {
+            return (L) new ArrayList<PresetElementPath>();
         }
     }),
     /**
@@ -119,8 +124,9 @@ public void teardown(final Main main, final Logic logic) {
         }
 
         @Override
-        public HashMap<String, String> getExtraTags(@NonNull Logic logic, @NonNull OsmElement e) {
-            HashMap<String, String> result = new HashMap<>();
+        public <M extends Map<String, String> & Serializable> M getExtraTags(@NonNull Logic logic, @NonNull OsmElement e) {
+            @SuppressWarnings("unchecked")
+            M result = (M) new HashMap<String, String>();
             // we only want to apply a level tag automatically to newly created objects if they don't already have the
             // tag and not when the filter is inverted
             Filter filter = logic.getFilter();
@@ -131,9 +137,10 @@ public HashMap<String, String> getExtraTags(@NonNull Logic logic, @NonNull OsmEl
             return result;
         }
 
+        @SuppressWarnings("unchecked")
         @Override
-        public ArrayList<PresetElementPath> getPresetItems(@NonNull Context ctx, @NonNull OsmElement e) {
-            return null;
+        public <L extends List<PresetElementPath> & Serializable> L getPresetItems(@NonNull Context ctx, @NonNull OsmElement e) {
+            return (L) new ArrayList<PresetElementPath>();
         }
     }), MODE_CORRECT(R.string.mode_correct, "CORRECT", true, true, true, false, null, R.drawable.unlocked_correct_white, new ModeConfig() {
 
@@ -181,8 +188,9 @@ public void teardown(final Main main, final Logic logic) {
         }
 
         @Override
-        public ArrayList<PresetElementPath> getPresetItems(@NonNull Context ctx, @NonNull OsmElement e) {
-            ArrayList<PresetElementPath> result = new ArrayList<>();
+        public <L extends List<PresetElementPath> & Serializable> L getPresetItems(@NonNull Context ctx, @NonNull OsmElement e) {
+            @SuppressWarnings("unchecked")
+            L result = (L) new ArrayList<PresetElementPath>();
             Preset[] presets = App.getCurrentPresets(ctx);
             if (presets.length > 0 && presets[0] != null) {
                 PresetItem pi = Preset.findBestMatch(presets, e.getTags(), null, null);
@@ -193,9 +201,10 @@ public ArrayList<PresetElementPath> getPresetItems(@NonNull Context ctx, @NonNul
             return result;
         }
 
+        @SuppressWarnings("unchecked")
         @Override
-        public HashMap<String, String> getExtraTags(@NonNull Logic logic, @NonNull OsmElement e) {
-            return null;
+        public <M extends Map<String, String> & Serializable> M getExtraTags(@NonNull Logic logic, @NonNull OsmElement e) {
+            return (M) new HashMap<String, String>();
         }
     }), MODE_VOICE(R.string.mode_voice, "VOICE", true, true, true, true, null, R.drawable.unlocked_voice_white, new FilterModeConfig() {
 
@@ -409,12 +418,13 @@ static Mode modeForTag(String tag) {
      * @param e the selected element
      * @return map containing the additional tags or null
      */
-    @Nullable
-    public HashMap<String, String> getExtraTags(@NonNull Logic logic, @NonNull OsmElement e) {
+    @SuppressWarnings("unchecked")
+    @NonNull
+    public <M extends Map<String, String> & Serializable> M getExtraTags(@NonNull Logic logic, @NonNull OsmElement e) {
         if (config != null) {
             return config.getExtraTags(logic, e);
         }
-        return null;
+        return (M) new HashMap<String, String>();
     }
 
     /**
@@ -424,12 +434,13 @@ public HashMap<String, String> getExtraTags(@NonNull Logic logic, @NonNull OsmEl
      * @param e the OsmElement
      * @return a List of PresetElementPath or null if none available
      */
-    @Nullable
-    public ArrayList<PresetElementPath> getPresetItems(@NonNull Context ctx, @NonNull OsmElement e) {
+    @SuppressWarnings("unchecked")
+    @NonNull
+    public <L extends List<PresetElementPath> & Serializable> L getPresetItems(@NonNull Context ctx, @NonNull OsmElement e) {
         if (config != null) {
             return config.getPresetItems(ctx, e);
         }
-        return null;
+        return (L) new ArrayList<PresetElementPath>();
     }
 
     /**
diff --git a/src/main/java/de/blau/android/ModeConfig.java b/src/main/java/de/blau/android/ModeConfig.java
index c019fe493..a926e29bf 100644
--- a/src/main/java/de/blau/android/ModeConfig.java
+++ b/src/main/java/de/blau/android/ModeConfig.java
@@ -1,9 +1,10 @@
 package de.blau.android;
 
-import java.util.ArrayList;
+import java.io.Serializable;
 import java.util.Collections;
 import java.util.EnumSet;
-import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 import android.content.Context;
@@ -41,7 +42,7 @@ public interface ModeConfig {
      * @return HashMap with tags to apply
      */
     @Nullable
-    HashMap<String, String> getExtraTags(@NonNull Logic logic, @NonNull OsmElement e);
+    <M extends Map<String, String> & Serializable> M getExtraTags(@NonNull Logic logic, @NonNull OsmElement e);
 
     /**
      * Called before PropertyEditor startup to provide any mode specific PresetItems
@@ -53,7 +54,7 @@ public interface ModeConfig {
      * @return list of PrestItems to apply
      */
     @Nullable
-    ArrayList<PresetElementPath> getPresetItems(@NonNull Context ctx, @NonNull OsmElement e);
+    <L extends List<PresetElementPath> & Serializable> L getPresetItems(@NonNull Context ctx, @NonNull OsmElement e);
 
     /**
      * Return the simple actions that are enabled in the menu
diff --git a/src/main/java/de/blau/android/propertyeditor/PresetSearchResultsFragment.java b/src/main/java/de/blau/android/propertyeditor/PresetSearchResultsFragment.java
index 87e05ee09..8256ed3bf 100644
--- a/src/main/java/de/blau/android/propertyeditor/PresetSearchResultsFragment.java
+++ b/src/main/java/de/blau/android/propertyeditor/PresetSearchResultsFragment.java
@@ -2,6 +2,7 @@
 
 import static de.blau.android.contract.Constants.LOG_TAG_LEN;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -48,7 +49,7 @@ public class PresetSearchResultsFragment extends DialogFragment implements Updat
 
     private static final int    TAG_LEN   = Math.min(LOG_TAG_LEN, PresetSearchResultsFragment.class.getSimpleName().length());
     private static final String DEBUG_TAG = PresetSearchResultsFragment.class.getSimpleName().substring(0, TAG_LEN);
-    
+
     private static final String SEARCH_RESULTS_KEY = "searchResults";
     private static final String SEARCH_TERM_KEY    = "searchTerm";
 
@@ -68,7 +69,7 @@ public class PresetSearchResultsFragment extends DialogFragment implements Updat
      * @param searchResults a List of PresetEements to display
      * @return an instance of PresetSearchResultsFragment
      */
-    public static PresetSearchResultsFragment newInstance(@NonNull String searchTerm, @NonNull ArrayList<PresetElement> searchResults) {
+    public static <L extends List<PresetElement> & Serializable> PresetSearchResultsFragment newInstance(@NonNull String searchTerm, @NonNull L searchResults) {
         PresetSearchResultsFragment f = new PresetSearchResultsFragment();
 
         Bundle args = new Bundle();
@@ -89,7 +90,6 @@ public void onAttach(Context context) {
         propertyEditorListener = (PropertyEditorListener) parent;
     }
 
-    @SuppressWarnings("unchecked")
     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
diff --git a/src/main/java/de/blau/android/propertyeditor/RelationMembersFragment.java b/src/main/java/de/blau/android/propertyeditor/RelationMembersFragment.java
index af6fde95d..71a62572e 100644
--- a/src/main/java/de/blau/android/propertyeditor/RelationMembersFragment.java
+++ b/src/main/java/de/blau/android/propertyeditor/RelationMembersFragment.java
@@ -2,6 +2,7 @@
 
 import static de.blau.android.contract.Constants.LOG_TAG_LEN;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -144,7 +145,7 @@ public Node getUnusedEnd() {
      * @return a new RelationMembersFragment instance
      */
     @NonNull
-    public static RelationMembersFragment newInstance(long id, ArrayList<RelationMemberDescription> members) {
+    public static <L extends List<RelationMemberDescription> & Serializable> RelationMembersFragment newInstance(long id, L members) {
         RelationMembersFragment f = new RelationMembersFragment();
 
         Bundle args = new Bundle();
diff --git a/src/main/java/de/blau/android/propertyeditor/TagEditorFragment.java b/src/main/java/de/blau/android/propertyeditor/TagEditorFragment.java
index 7c08cef40..8570feca0 100644
--- a/src/main/java/de/blau/android/propertyeditor/TagEditorFragment.java
+++ b/src/main/java/de/blau/android/propertyeditor/TagEditorFragment.java
@@ -334,7 +334,7 @@ public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup c
         // Add any extra tags that were supplied
         @SuppressWarnings("unchecked")
         Map<String, String> extraTags = Util.getSerializeable(getArguments(), EXTRA_TAGS_KEY, HashMap.class);
-        if (extraTags != null) {
+        if (extraTags != null && !extraTags.isEmpty()) {
             for (Entry<String, String> e : extraTags.entrySet()) {
                 addTag(editRowLayout, e.getKey(), e.getValue(), true, false);
             }
@@ -357,7 +357,7 @@ public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup c
 
         if (savedInstanceState == null) { // the following should only happen once on initial creation
             List<PresetElementPath> presetsToApply = Util.getSerializeableArrayList(getArguments(), PRESETSTOAPPLY_KEY, PresetElementPath.class);
-            if (presetsToApply != null && !presetsToApply.isEmpty()) {
+            if (Util.notEmpty(presetsToApply)) {
                 FragmentActivity activity = getActivity();
                 Preset preset = App.getCurrentRootPreset(activity);
                 PresetGroup rootGroup = preset.getRootGroup();