BPMN2 — Correlation on message flow and choreography activities

Should be able to specify correlation directly on message flow and
choreography activities, without the overhead of conversations.

Choreography activities are a way of grouping message flow and should
have correlation like other message flow grouping constructs. Message
flows themselves do not need correlation, because correlation only works
if the same key values are in more than one message flow, as identified
by message flow grouping constructs.
Remove Subsection 12.3.3 (Correlations) and the sentence in it.
In Figure 12.6 (The metamodel segment for a Choreography Activity) add
the CorrelationKey metaclass with a unidirectional association to it
from ChoreographyActivity. This association has multiplicity 0..1 on
the ChoreographyActivity end and * on the CorrelationKey end. The
association end on the CorrelationKey end is named correlationKeys, which
has composite aggregation (the black diamond appears on the opposite
end).
In Table 12.2 (Choreography Activity Model Associations) add a row at
the end:

• correlationKeys : CorrelationKey [0..*]
  This association specifies correlationKeys used by the message flow
  in the choreography activity, including subchoreographies and called
  choreographies.
  In Table 12.11 (ChoreographyActivity XML schema), after the
  participantRef element attribute, insert on a new line:
  <xsd:element ref="correlationKeys" minOccurs="0" maxOccurs="unbounded"/>
  Disposition: Resolved