Index: trunk/src/org/openstreetmap/josm/data/osm/Tagged.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/Tagged.java	(revision 15471)
+++ trunk/src/org/openstreetmap/josm/data/osm/Tagged.java	(revision 15472)
@@ -143,5 +143,6 @@
      */
     default boolean hasTag(String key, Collection<String> values) {
-        return values.contains(get(key));
+        String v = get(key);
+        return v != null && values.contains(v);
     }