code: @Override
    public boolean containsKey(Object o) {
      @SuppressWarnings("unchecked")
      final K key = (K) o;
      return binarySearchInArray(key) >= 0 || overflowEntries.containsKey(key);
    }
docs: The implementation throws a {@code ClassCastException} if o is not an
  object of type {@code K}.
  
  {@inheritDoc}