Index: trunk/src/org/openstreetmap/josm/data/Data.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/Data.java	(revision 11093)
+++ trunk/src/org/openstreetmap/josm/data/Data.java	(revision 11095)
@@ -22,5 +22,7 @@
      * @return Area object encompassing downloaded data.
      */
-    Area getDataSourceArea();
+    default Area getDataSourceArea() {
+        return DataSource.getDataSourceArea(getDataSources());
+    }
 
     /**
@@ -36,4 +38,6 @@
      * bounds are defined.
      */
-    List<Bounds> getDataSourceBounds();
+    default List<Bounds> getDataSourceBounds() {
+        return DataSource.getDataSourceBounds(getDataSources());
+    }
 }
Index: trunk/src/org/openstreetmap/josm/data/gpx/GpxData.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/gpx/GpxData.java	(revision 11093)
+++ trunk/src/org/openstreetmap/josm/data/gpx/GpxData.java	(revision 11095)
@@ -2,12 +2,11 @@
 package org.openstreetmap.josm.data.gpx;
 
-import java.awt.geom.Area;
 import java.io.File;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Date;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedList;
-import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
@@ -470,15 +469,5 @@
     @Override
     public Collection<DataSource> getDataSources() {
-        return dataSources;
-    }
-
-    @Override
-    public Area getDataSourceArea() {
-        return DataSource.getDataSourceArea(dataSources);
-    }
-
-    @Override
-    public List<Bounds> getDataSourceBounds() {
-        return DataSource.getDataSourceBounds(dataSources);
+        return Collections.unmodifiableCollection(dataSources);
     }
 
Index: trunk/src/org/openstreetmap/josm/data/osm/DataSet.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/DataSet.java	(revision 11093)
+++ trunk/src/org/openstreetmap/josm/data/osm/DataSet.java	(revision 11095)
@@ -4,5 +4,4 @@
 import static org.openstreetmap.josm.tools.I18n.tr;
 
-import java.awt.geom.Area;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -24,5 +23,4 @@
 
 import org.openstreetmap.josm.Main;
-import org.openstreetmap.josm.data.Bounds;
 import org.openstreetmap.josm.data.Data;
 import org.openstreetmap.josm.data.DataSource;
@@ -923,10 +921,5 @@
     @Override
     public Collection<DataSource> getDataSources() {
-        return dataSources;
-    }
-
-    @Override
-    public Area getDataSourceArea() {
-        return DataSource.getDataSourceArea(dataSources);
+        return Collections.unmodifiableCollection(dataSources);
     }
 
@@ -1328,9 +1321,4 @@
     }
 
-    @Override
-    public List<Bounds> getDataSourceBounds() {
-        return DataSource.getDataSourceBounds(dataSources);
-    }
-
     /**
      * Moves all primitives and datasources from DataSet "from" to this DataSet.