Not able to set Suitelet Sublist in 2.0 Client Script

I'm attempting to use currentRecord.setSublistValue for a Suitelet sublist using a client script but I get the error "TypeError currentRecord.setSublistValue is not a function.

The client script is using validateField as the trigger.

Has anyone else run into this with SuiteScript 2.0?

I'm able to use currentRecord.setValue for a field on the Suitelet and set its value but can't set a list sublist.

I've tried:

 currentRecord.setSublistValue({                      sublistId: 'custpage_mysublist',                      fieldId: 'custpage_mysublistfield',                      line: 0,                      value: 'TEST'                  }); 

and...

 var mySublistObj = currentRecord.getSublist({                  sublistId: 'custpage_mysublist'              });  mySublistObj.setSublistValue({                      id: 'custpage_mysublistfield',                      line: 0,                      value: 'TEST'                  });