Do not consider null values duplicates when importing

[nolanpro]

Issue & Reproduction Steps

Required for https://github.com/ProcessMaker/package-data-sources/pull/307

Occasionally we need to temporarily set a foreign key to null until all the models are saved and we have a new key for it. To support this, we should not consider null values duplicates.

Solution

• Skip checking duplicates if the value is null

How to Test

• See jira issue

Related Tickets & Packages

• https://github.com/ProcessMaker/package-data-sources/pull/307
• https://processmaker.atlassian.net/browse/FOUR-9646

Code Review Checklist

• I have pulled this code locally and tested it on my instance, along with any associated packages.
• This code adheres to ProcessMaker Coding Guidelines.
• This code includes a unit test or an E2E test that tests its functionality, or is covered by an existing test.
• This solution fixes the bug reported in the original ticket.
• This solution does not alter the expected output of a component in a way that would break existing Processes.
• This solution does not implement any breaking changes that would invalidate documentation or cause existing Processes to fail.
• This solution has been tested with enterprise packages that rely on its functionality and does not introduce bugs in those packages.
• This code does not duplicate functionality that already exists in the framework or in ProcessMaker.
• This ticket conforms to the PRD associated with this part of ProcessMaker.

ci:package-data-sources:bugfix/FOUR-9646

[agustinbusso]

The fix is correct, the PM block can be created and assigned correctly:

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