Index: trunk/src/org/openstreetmap/josm/data/osm/DataSet.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/DataSet.java	(revision 11629)
+++ trunk/src/org/openstreetmap/josm/data/osm/DataSet.java	(revision 11632)
@@ -133,4 +133,9 @@
 
     /**
+     * All data sources of this DataSet.
+     */
+    private final Collection<DataSource> dataSources = new LinkedList<>();
+
+    /**
      * Constructs a new {@code DataSet}.
      */
@@ -472,9 +477,4 @@
         return relations.contains(r);
     }
-
-    /**
-     * All data sources of this DataSet.
-     */
-    public final Collection<DataSource> dataSources = new LinkedList<>();
 
     /**