@Override
  public Object evaluate(ExecutionContext context) throws FunctionDomainException,
      TypeMismatchException, NameResolutionException, QueryInvocationTargetException {
    throw new UnsupportedOperationException(
        "Not to be evaluated directly");
  }
Returns a RuntimeIterator (or null if evaluates to null or UNDEFINED); the collection expr is
evaluated lazily after dependencies are known
geode-core/src/main/java/org/apache/geode/cache/query/internal/CompiledIteratorDef.java