[Rails5] The property '#/lock_version' of type integer did not match one or more of the following types: string, null

Note: add rails5 to a branch name to trigger rails5 specific CI jobs.

https://gitlab.com/gitlab-org/gitlab-ce/-/jobs/75037446

Failures:

  1) IssueSerializer non-sidebar issue serialization matches issue json schema
     Failure/Error: JSON::Validator.validate!(SchemaPath.expand(schema, dir), data, options)

     JSON::Schema::ValidationError:
       The property '#/lock_version' of type integer did not match one or more of the following types: string, null
     # ./spec/support/api/schema_matcher.rb:23:in `block (2 levels) in <top (required)>'
     # ./spec/serializers/issue_serializer_spec.rb:16:in `block (3 levels) in <top (required)>'

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1572 examples, 1 failure, 1 pending