Hi,
 
 Using the association to connect a Group with a Group results in an exclamation mark and let the consistency checks on the model fail. According to the BPMN-Meta Model an Association from BPMN:Artifacts-Package allows incoming and outgoing connections to any BPMN:BaseElement (see diagram in BPMN 2.0.2 on page 65). This means Association from Group to Group is valid and should not break consistency checks nor result in an exclamation mark.
 
 In GraphRep of Association the following lines should be removed to confirm with BPMN-Standard in Version 2.0.2:
 
  ELSIF (((fromType = "Group") OR (fromType = "Text Annotation")) AND ((toType = "Group") OR (toType = "Text Annotation")))
  TEXT "!" x:0.1cm y:0.0cm w:l h:b   
 
Thanks,
Thomas