public V replace(int key, V value) {
    if (value == null) {
      throw new NullPointerException();
    }
    int hash = hash(key);
    return segmentFor(hash).replace(key, hash, value);
  }
@return the previous value associated with the specified key, or <tt>null</tt> if there was no
        mapping for the key
@throws NullPointerException if the specified key or value is null
geode-core/src/main/java/org/apache/geode/internal/ObjIdConcurrentMap.java