@Override
    public boolean contains(Object o) {
      if (!(o instanceof Entry)) {
        return false;
      }
      Entry e = (Entry) o;
      Entry candidate = getEntry(e.getKey());
      return candidate != null && candidate.equals(e);
    }
Returns a {@link Set} view of the mappings contained in this map. The set is backed by the map,
so changes to the map are reflected in the set, and vice-versa. If the map is modified while an
iteration over the set is in progress (except through the iterator's own <tt>remove</tt>
operation, or through the <tt>setValue</tt> operation on a map entry returned by the iterator)
the results of the iteration are undefined. The set supports element removal, which removes the
corresponding mapping from the map, via the <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
<tt>removeAll</tt>, <tt>retainAll</tt> and <tt>clear</tt> operations. It does not support the
<tt>add</tt> or <tt>addAll</tt> operations.

@return a set view of the mappings contained in this map
geode-core/src/main/java/org/apache/geode/cache/query/internal/ObjectIntHashMap.java