UMLR — An Activity Edge cannot connect to Activities

Problem:
A CommunicationPath is a ActivityEdge. An ActivityEdge has source and target properties of type ActivityNode. But an Activity is not an ActivityNode. So the CommunicationPath link vom Activity to Activity is invalid.
Such a link should be valid - otherwise the diagram in 15.5.5 Examples is wrong.

Info: Some tools seem to simply allow this:
<ownedBehavior xmi:type="uml:Activity" xmi:id="EAID_940293B7_001A_4d5d_BCFE_24CB874155E3" name="Create Title Entry" visibility="public" isReadOnly="false" isSingleExecution="false">
...
<edge xmi:type="uml:ControlFlow" xmi:id="EAID_B750FB8E_8132_4569_99C2_8C0DFD11F144" visibility="public" source="EAID_940293B7_001A_4d5d_BCFE_24CB874155E3" target="EAID_D4190768_7F03_4546_B5E5_38E4DBE56F19"/>
or
https://github.com/awarnke/crystal_facet_uml/blob/master/example_diagrams/export_test/export_test_15_activity.xmi

Proposed fix: Would it make sense to make an Activity derive from ActivityNode instead of Behavior, and ActivityNode derived from Behavior?

Maybe i simply understood the current specification wrong - then please ignore my Comment.
Regards
A. Warnke