// Check all iterators for correct size counts
 private void checkSizes(int expectedSize) {
   assertEquals("size()", _nbhm.size(), expectedSize);
   Collection<String> vals = _nbhm.values();
   checkSizes("values()", vals.size(), vals.iterator(), expectedSize);
   Set<String> keys = _nbhm.keySet();
   checkSizes("keySet()", keys.size(), keys.iterator(), expectedSize);
   Set<Entry<String, String>> ents = _nbhm.entrySet();
   checkSizes("entrySet()", ents.size(), ents.iterator(), expectedSize);
 }