public boolean containsKey(Object key) {
    return getEntry(key) != null;
  }
Returns <tt>true</tt> if this map contains a mapping for the specified key.

@param key The key whose presence in this map is to be tested
@return <tt>true</tt> if this map contains a mapping for the specified key.
geode-core/src/main/java/org/apache/geode/cache/query/internal/ObjectIntHashMap.java