Move to_param to to_query, also Improve tests
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
Merge pull request #16328 from noinkling/template_password_confirmation_fix

Give password_confirmation div the "field" class in the scaffold generator "_form" partial
[ci skip] fix doc typo for validates_uniqueness_of
Merge pull request #16332 from shizm/fix-docs-validates-uniqueness-of

[ci skip] fix doc typo for validates_uniqueness_of
Move array test files under array
docs, cleanup mixed indents within `form_options_helper.rb` RDoc.

[ci skip]

This fixes the broken code block rendering and indents the examples
within the parameter list.
Merge pull request #16334 from akshay-vishnoi/array-tests

Move array test files under array
Add missing test case for Array#to_sentence, collect all test cases for Object#to_param at one place and avoid repitition