code: public boolean containsValue(Object value) {
          Node<K,V>[] tab; V v;
          if ((tab = table) != null && size > 0) {
              for (int i = 0; i < tab.length; ++i) {
                  for (Node<K,V> e = tab[i]; e != null; e = e.next) {
                      if ((v = e.value) == value ||
                          (value != null && value.equals(v)))
                          return true;
                  }
              }
          }
          return false;
      }
docs: Returns <tt>true</tt> if this map maps one or more keys to the
  specified value.
  
  @param value value whose presence in this map is to be tested
  @return <tt>true</tt> if this map maps one or more keys to the
  specified value