fix 7444 "resurfacing" of nested contained defined object and adding …

[gurubook]

Description of the PR

Code generation on operation that return object in "nested" array/map does not add the required definition to the import list. This revised patch address the issue saving the contained object type during the recursion.

Specs demostrating this ussye is in modules/swagger-codegen/src/test/resources/2_0/return-nested.yaml

This should solve issue #7444

[swagger-bot]

Hey Meat Bag! Your Pull Request Build Passed! 743 tests run, 5 skipped, 0 failed.