guard null field values in BPMN User Task Instructions

[hi-ko]

In BPMN user tasks you can use placeholders for entity fields like

{$customField}

. When the field value is null (I used url-type), the Instructions parses to

{$customField}

(the expression as string) instead of an empty string. Is this a bug or do I need to guard these fields by conditions myself?
Tested with Advance Pack 2.15.0

[yuri]

Not a bug.