Update notebook node to allow multiple input links

[vabarbosa]

Fixes #750

This addresses the issue of cardinality incorrectly being set to a max: 0 and thus not allowing multiple input links on the notebook node.

The second observation(cardinality being deleted after first node) was addressed in canvas (elyra-ai/canvas#162) and should be part of the next canvas release.

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[kevin-bates]

LGTM - thanks Va!

[lresende]

Do we know what happens if we don't specify cardinality info for the nodes? Are there an acceptable default?

[ajbozarth]

As far as we've seen having no cardinality behaves the same as we would like it to

[kevin-bates]

Although we see a behavior of min: 0, max: -1, the schema imposes an "at least 1" default while the comment in the description indicates an "exactly 1" (min: 1, max: 1) behavior for inputs and an "at least 1" (min: 1, max: -1) behavior for outputs. So they might have a bug when cardinality is not specified (IMO).

All the more reason to update the canvas for 1.0.

[lresende]

The answer to my original question:

The original intent for palettes was to load selected operators from an operator repository. The operator definition includes “cardinality” for the “port_definition”: https://github.com/elyra-ai/pipeline-schemas/blob/master/common-pipeline/operators/operator-v3-schema.json.
The description for “cardinality” is:
“Property to capture how many connections are allowed for this port, e.g., min: 1, max:1 implies you must supply 1 and only 1; min:0, max:1 implies it is optional and a max of one, min:0, max:-1 means it is optional and you can have any number of connections. The default value is 1:1 for inputs and 1:-1 for outputs.”

[kevin-bates]

Sounds like what I said and referenced. I should win a prize: 🎉 😄

For ports with cardinality min > 0, when does that get enforced? Is there some call to make to "validate a pipeline" prior to its submission?