Major Description
Expressions used in policy-conditions/row-filters might evaluate to null value i.e., like when the attribute referenced doesn't exist. In such cases, the evaluator returns string 'null'. Instead, an empty string would be a better return value in such case. This would also enable use of variables in sub-expressions, like:
${{var d = USER.deptCode;}} dept == ${{d}}
With the current implementation, following value is returned for above expression, assuming USER.deptCode is 10:
null dept == 10
This is caused by the first expression, ${{var d = USER.deptCode{}}}, returning null.