Index: trunk/src/org/openstreetmap/josm/gui/io/importexport/GeoJSONExporter.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/io/importexport/GeoJSONExporter.java	(revision 12805)
+++ trunk/src/org/openstreetmap/josm/gui/io/importexport/GeoJSONExporter.java	(revision 12806)
@@ -36,5 +36,5 @@
         if (layer instanceof OsmDataLayer) {
             try (Writer out = Files.newBufferedWriter(file.toPath(), StandardCharsets.UTF_8)) {
-                out.write(new GeoJSONWriter((OsmDataLayer) layer).write());
+                out.write(new GeoJSONWriter(((OsmDataLayer) layer).data).write());
             }
         } else {
Index: trunk/src/org/openstreetmap/josm/io/GeoJSONWriter.java
===================================================================
--- trunk/src/org/openstreetmap/josm/io/GeoJSONWriter.java	(revision 12805)
+++ trunk/src/org/openstreetmap/josm/io/GeoJSONWriter.java	(revision 12806)
@@ -43,5 +43,5 @@
 public class GeoJSONWriter {
 
-    private final OsmDataLayer layer;
+    private final DataSet data;
     private final Projection projection;
     private static final boolean SKIP_EMPTY_NODES = true;
@@ -51,7 +51,18 @@
      * @param layer The OSM data layer to save
      * @since 10852
-     */
+     * @deprecated To be removed end of 2017. Use {@link #GeoJSONWriter(DataSet)} instead
+     */
+    @Deprecated
     public GeoJSONWriter(OsmDataLayer layer) {
-        this.layer = layer;
+        this(layer.data);
+    }
+
+    /**
+     * Constructs a new {@code GeoJSONWriter}.
+     * @param ds The OSM data set to save
+     * @since 12806
+     */
+    public GeoJSONWriter(DataSet ds) {
+        this.data = ds;
         this.projection = ProjectionPreference.wgs84.getProjection();
     }
@@ -79,6 +90,6 @@
                     .add("type", "FeatureCollection")
                     .add("generator", "JOSM");
-            appendLayerBounds(layer.data, object);
-            appendLayerFeatures(layer.data, object);
+            appendLayerBounds(data, object);
+            appendLayerFeatures(data, object);
             writer.writeObject(object.build());
             return stringWriter.toString();