@Override
  public Object evaluate(ExecutionContext context) {
    Support.Assert(current != UNINITIALIZED,
        "error to evaluate RuntimeIterator without setting current first");
    return current;
  }
(Re)evaluate in the context of the current iterations through the cross-product. If this
iterator is not dependent on the current iteration, then just return the previously evaluated
collection. Otherwise, re-evaluate. Returns null if the collection itself is null or UNDEFINED
geode-core/src/main/java/org/apache/geode/cache/query/internal/RuntimeIterator.java