@Override
    public Object evaluate(ExecutionContext context) throws FunctionDomainException,
        TypeMismatchException, NameResolutionException, QueryInvocationTargetException {
      return context.getCurrentProjectionField();
    }
evaluates sort criteria in order by clause
geode-core/src/main/java/org/apache/geode/cache/query/internal/CompiledSortCriterion.java