Unable to serialize empty TabularData

[sakno]

Jolokia can't serialize TabularDataSupport with empty set of rows. In this case value field in the HTTP response contains null value:

{"timestamp":1433455091,"status":200,"request":{"mbean":"helloworld:type=SimpleMBean","attribute":"simpleAttribute","type":"read"},"value":null}

I found the reason. Look at this line of code:
TabularDataExtractor.java L200

When TabularData is empty the loop never iterates and found local variable will set to false. So AttributeFilteredException will cause to unwind call stack and catched in ObjectToJsonConverter.extractObjectWithContext method.

try {
            jsonResult = extractObject(pValue, pExtraArgs, pJsonify);
        } catch (ValueFaultHandler.AttributeFilteredException exp) {
            jsonResult = null;
        } finally {
            clearContext();
        }

Here, jsonResult always set to null if AttributeFilteredException exception occurred.

[nevenr]

Hi,

I assumed that empty TabularData should respond to empty JSON object.
Fix is nevenr@73afe34.
This commit will be included in #220.

Regards,
N.

[rhuss]

Fixed in master