Service request test condition of null value FAIL

Service request test condition of null value FAIL

Hello, 
i have a deluge script where i test if a value of a field is null.

info requestObj.get('subcategory');
info (requestObj.get('subcategory') == null );
info (requestObj.get('subcategory') == 'null');
info (requestObj.get('subcategory') == "null");
info (requestObj.get('subcategory') != null );
info (requestObj.get('subcategory') != 'null');
info (requestObj.get('subcategory') != "null");

result : 


in case you did not notice the return value is null
i need a fix A.S.A.P

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