Change ActionController::Parameters#require behavior when value is empty
When the value for the required key is empty an ActionController::ParameterMissing is raised which gets caught by ActionController::Base and turned into a 400 Bad Request reply with a message in the body saying the key is missing, which is misleading.

With these changes, ActionController::EmptyParameter will be raised which ActionController::Base will catch and turn into a 400 Bad Request reply with a message in the body saying the key value is empty.
Test with the right association
remove warnings on ruby trunk
Merge pull request #12739 from laurocaetano/remove_warnings_for_ruby_trunk

Remove warnings on ruby trunk
Fix wrong behavior where associations with dependent: :destroy options
was using nullify strategy

This caused a regression in applications trying to upgrade.

Also if the user set the dependent option as destroy he expects to get
the records removed from the database.
Merge pull request #9660 from sebasoga/change_strong_parameters_require_behaviour

Change ActionController::Parameters#require behavior when value is empty