IBX-7055: Allowed to return `null` when content is not deleted #1439

Job	Run time
Run code style check (8.0)	2m 52s
Unit tests & SQLite integration tests (7.4)	6m 52s
Solr integration tests (7.4)	9m 53s
Unit tests & SQLite integration tests (8.0)	7m 17s
Solr integration tests (8.0)	10m 48s
Unit tests & SQLite integration tests (8.1)	7m 25s
Solr integration tests (8.1)	9m 43s
MySQL integration tests (7.4)	13m 11s
MySQL integration tests (8.0)	12m 32s
PostgreSQL integration tests (7.4)	19m 29s
MySQL integration tests (8.1)	12m 50s
PostgreSQL integration tests (8.0)	22m 27s
PostgreSQL integration tests (8.1)	24m 45s
	2h 40m 4s

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