Index: /applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/Tile.java
===================================================================
--- /applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/Tile.java	(revision 28410)
+++ /applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/Tile.java	(revision 28411)
@@ -282,6 +282,14 @@
     }
 
+    /**
+     * Puts the given key/value pair to the metadata of the tile.
+     * If value is null, the (possibly existing) key/value pair is removed from 
+     * the meta data.
+     * 
+     * @param key
+     * @param value 
+     */
     public void putValue(String key, String value) {
-        if (value == null || "".equals(value)) {
+        if (value == null || value.isEmpty()) {
             if (metadata != null) {
                 metadata.remove(key);