Move to_param to to_query, also Improve tests
Remove finishing? method from transaction.

The finishing variable on the transaction object was a work-around for
the savepoint name, so after a rollback/commit the savepoint could be
released with the previous name.

related:
9296e6939bcc786149a07dac334267c4035b623a
60c88e64e26682a954f7c8cd6669d409ffffcc8b
Added nodoc to change_table
Transactions refactoring

Add a transaction manager per connection, so it can controls the
connection responsibilities.

Delegate transaction methods to transaction_manager
savepoint_name should return nil for non-savepoint transactions

Also add test to assets the savepoint name
Merge pull request #16284 from arthurnn/transactions

Transactions refactoring
Extract the transaction class to a local variable
Merge pull request #16305 from tomkadwill/documented_change_table

Added documentation for change_table
remove some caching

this caching doesn't increase performance, but does increase complexity.
remove it for now and find better ways to speed up this code.
remove the mounted? method

we know the routes should not be "optimized" when mounting an
application
remove blank lines in the start of the ActiveRecord files
Merge pull request #16326 from itsNikolay/remove_blank_lines

remove blank lines at the start of the ActiveRecord files
Move object test files under object
Merge pull request #15658 from akshay-vishnoi/object-tests

Move object test files under object
Merge pull request #15629 from akshay-vishnoi/test-to_param

Define Hash#to_query and set Hash#to_param as alias to it; with test cases
Give password_confirmation div the "field" class in erb form template
Added failing test case for #16131
Fixed a compatibility issue with the `Oj` gem

`Time#as_json`, `Date#as_json` and `DateTime#as_json` incorrectly depends on a
delegation that is set up in `active_support/json/encoding`. We cannot simply
require that file in `core_ext/object/json` because it would cause a circular
dependency problem (see #12203 for background). We should instead rely on AS's
autoload to load that file for us on-demand.

To trigger autoload correctly, we need to reference the `AS::JSON::Encoding`
constant instead of using the delegated version.

Fixes #16131.
Raise an exception when attachments are added after `mail` was called.

Closes #16163

Adding attachments after a call to `mail` will result in invalid emails.
This is related to the fact, that `mail` is making the required preparations
before the email is ready to be sent. These change depending on your
added attachments.
Merge pull request #16148 from rails/fix_json_autoload

Fix json autoload