public EntryIterator iterator() {
    return new EntryIterator();
  }
Returns an iterator over the {@link Entry}s of this map. Note that this iterator is <b>not</b>
fail-fast. That is, it is the user's responsibility to ensure that the map does not change
while it is being iterated over.
geode-core/src/main/java/org/apache/geode/internal/admin/ListenerIdMap.java