remove deprecated DescriptiveParallelContributor model

[ndushay]

DescriptiveParallelContributor class is marked deprecated: https://github.com/sul-dlss/cocina-models/blob/main/lib/cocina/models/descriptive_parallel_contributor.rb#L5

https://github.com/sul-dlss/cocina-models/blob/main/openapi.yml#552

Can it be removed?

Arcadia says "parallelContributor was never in use"

Steps

• write a report to ensure it's not used (if it is, have Arcadia change those objects)
• take it out of the API and the code (by regenerating models) ... and go through the cocina gem release process.

NOTE that this is the only thing marked deprecated in the cocina-models openapi.yml file

[ndushay]

no occurences found in DROs or Collections, using property_existence*.rb reports from #4245

[ndushay]

Correction: there are lots of EMPTY occurrences of parallelContributor ...

[justinlittman]

So does that mean this is un-removable?

[jcoyne]

@justinlittman I think we could remove it by making it optional, omitable, and changing the default to nil. Then we can rewrite any/all descriptive metadata that has parallelContributor: []

[ndushay]

I don't think the cost of always putting in empty arrays should be "we can never omit an array property from the model."

[ndushay]

reran reports today; still no non-empty values for parallelContributor for collections or DROs. starting work on PR to

(from JCoyne:)

I think we could remove it by making it optional, omitable, and changing the default to nil. Then we can rewrite any/all descriptive metadata that has parallelContributor: []