[ci skip] Fix typo of `collection=` method.
[ci skip] Fix typo of `collection_singular_ids=` method.
Correctly detect mutation on serialized columns mapping to binary

Fixes #16701
[ci skip] Update 4_2_release notes
Use less iterations for KeyGenerator in tests

This commit improves performance of cookie tests:

Ruby  |   After  |   Before
----- | --------:| --------:
MRI   |    5.03s |     9.28s
JRuby |   25.45s |  1648.23s

Please note the improvement for JRuby.
Map controller to integration tests.
Recycle `request` everytime `process` is called.
Remove the need to predefine a set of allowed headers.
Reject parameters that are used in the URL.
Response object is now an instance of ActionDispatch::TestResponse.
Make sure `REQUEST_METHOD` is set for every test process.
Test should follow Controller naming convention.
Test should follow Controller naming convention.
Test should follow Controller naming convention.
No need to override `controller_path`.
No need to override `controller_path`.
[FIXME] Add action directly to `PATH_INFO`.
Add acronym and remvoe controller_path.
Add PATCH and DELETE routes.
Follow Controller naming convention.