Merge 2.20.x up into 2.21.x

…2.21.x_3Yg2ZYgM

Merge release 2.20.1 into 2.21.x

* 2.20.x:
  Introduce testNotListedValueInEnumArray
  Fix documentation for JoinColumn nullable (doctrine#11798)
  Ignore deprecations from doctrine/common
  Fix fields of transient classes being considered duplicate with `reportFieldsWhereDeclared`

…2.21.x_8O8nHxqC

Merge release 2.20.2 into 2.21.x

If scheduleForInsert was called in prePersist hook already, then persistNew need to check this case first, otherwise a ORMInvalidArgumentException will be thrown

…2.21.x_KkdqS0u7

Merge release 2.20.3 into 2.21.x

…ocking_test

Add functional strict-locking 2nd level cache test

When the persister is extended to do a multi update, the caching is not
wanted. The impact is minimal as the CPU/time overhead per query is
much bigger and the prepared statement is not cached anyway.

The new variable name is much more clearer.

…persister

Improve BasicEntityPersister to be more flexible and cleaner

Fix JoinedSubclassPersister as BasicEntityPersister was already fixed in doctrineGH-10735.

The fix can be verified by modifying UnitOfWork to execute `BasicEntityPersister::executeInserts()` for multiple entities at once for the same entity class/persister instance - https://github.com/doctrine/orm/blob/2.20.3/src/UnitOfWork.php#L1186 - then reproducible on `Doctrine\Tests\ORM\Functional\Ticket\GH10531Test::testInserts` test.

As extending/modifying UnitOfWork in tests in not easily possible, I submit this fix for v2.x without a test.

…ersister_insert_of_multiple_entities

Fix JoinedSubclassPersister when multiple entities are inserted

…upported-branches-on-README

doc: update supported branches on README (2.20.x)

Inserts without post-inserted ID can be sent to DB grouped together
hence the extra test.

…ersist

fix: calling scheduleForInsert twice

…ount_query_test

Add 2nd level cache test for insert without post-inserted ID

Fix broken comments