public boolean containsKey(int key) {

    Entry[] table = this.table;
    int bucket = Math.abs(key) % table.length;
    for (Entry e = table[bucket]; e != null; e = e.next) {
      if (e.key == key) {
        return true;
      }
    }

    return false;
  }
Returns <code>true</code> if this map contains a mapping for the given key.

@throws IllegalArgumentException <code>key</code> is less than zero
geode-core/src/main/java/org/apache/geode/internal/ObjIdMap.java