Replacing a node with a group workflow when it receives a visualizer mapping generates a bogus source node

[PathogenDavid]

This is something that came up when Gonçalo and I were discussing #1769

Starting with the following workflow: ReplaceNodeWithGroupWorkflowIssue.zip

Select the Untitled PublishSubject node. Replace it with a GroupWorkflow node (IE: using the "Replace" option from the context menu in the Toolbox.)

This results in the following within the main workflow:

But within the group workflow you'll see there's a bogus Source2 (presumably added for the dashed connection for the visualizer mapping.)

This source shouldn't be here (and in fact does nothing) as visualizer mappings conceptually apply to the node itself rather than any of its sources.

[glopesdev]

@PathogenDavid related to this, I found out that grouping the PublishSubject with GroupWorkflow (rather than replacing) results in a different (and possibly unwanted) behavior:

Basically the current behavior of grouping is to eliminate all dashed connections (ExternalizedProperty, VisualizerMapping, etc) to the newly created group. This is probably not ideal and we might want to revisit this in a separate proposal.

[PathogenDavid]

@glopesdev Yeah that doesn't seem ideal. I created a separate issue for it here: #1959