protected int index(Object obj) {
    return index(_imqEvaluator.evaluateKey(obj), obj);
  }
Locates the index of <tt>obj</tt>.

@param obj an <code>Object</code> value, expected to be the value object
@return the index of <tt>obj</tt> or -1 if it isn't in the set.
geode-core/src/main/java/org/apache/geode/cache/query/internal/index/HashIndexSet.java