They may be cached for existing apps upgrading to 6.1. Follows up on #34477.

Fix through association to respect source scope for `includes`/`preload`

Decoding JSON dates should respect newlines

This fixes tests for missing backtraces

Errors *should* output their stack. Somehow these tests were passing
before. This clarifies all states (skip/fail/error) and works against
@tenderlove's patch.

`reflection.scope` is not aware of all source scopes if the association
is through association.

It should use `reflection.join_scopes` for that.

Fixes #39376.

Updates to nokogiri 1.10.9

Add `ActionDispatch::ActionableExceptions` to default middleware docs

Before #39304 was merged, backtraces would look like this:

```
$ be ruby -I lib:test test/controller/request_forgery_protection_test.rb -n test_ignores_trailing_slash_during_generation
Run options: -n test_ignores_trailing_slash_during_generation --seed 22205

E

Error:
PerFormTokensControllerTest#test_ignores_trailing_slash_during_generation:
NoMethodError: undefined method `have_cookie_jar?' for #<Object:0x00007f9ce19b9620>
    /Users/aaron/git/rails/actionpack/lib/action_controller/test_case.rb:522:in `ensure in process'
    /Users/aaron/git/rails/actionpack/lib/action_controller/test_case.rb:542:in `process'
    /Users/aaron/git/rails/actionpack/lib/action_controller/test_case.rb:395:in `get'
    test/controller/request_forgery_protection_test.rb:1005:in `test_ignores_trailing_slash_during_generation'

rails test test/controller/request_forgery_protection_test.rb:1004

Finished in 0.213230s, 4.6898 runs/s, 0.0000 assertions/s.
1 runs, 0 assertions, 0 failures, 1 errors, 0 skips
```

After #39304 was merged they look like this:

```
$ be ruby -I lib:test test/controller/request_forgery_protection_test.rb -n test_ignores_trailing_slash_during_generation
Run options: -n test_ignores_trailing_slash_during_generation --seed 62892

E

Error:
PerFormTokensControllerTest#test_ignores_trailing_slash_during_generation:
NoMethodError: undefined method `have_cookie_jar?' for #<Object:0x00007fa6d60193c8>

rails test test/controller/request_forgery_protection_test.rb:1004

Finished in 0.211953s, 4.7180 runs/s, 0.0000 assertions/s.
1 runs, 0 assertions, 0 failures, 1 errors, 0 skips
```

This patch reverts the part of #39304 that removes the backtrace.

Fixes #39088.

Resolve conflict between counter cache and optimistic locking

Satisfy Rubocop

Fixes offense:

```
actionpack/test/journey/router_test.rb:493:37: C: Style/HashSyntax: Use the new Ruby 1.9 hash syntax.
            options = options.merge(:_recall => recall)
                                    ^^^^^^^^^^^
```

Bump an Active Record instance's lock version after updating its counter
cache. This avoids raising an unnecessary ActiveRecord::StaleObjectError
upon subsequent transactions by maintaining parity with the
corresponding database record's lock_version column.

Journey is considered internal, and I would like to stop testing
internals so that we are free to refactor.  This commit just moves us up
one more call frame with the goal if getting closer to a public API.
Once we're up the stack high enough that we're testing a public API we
can stop

Unify raise_on_missing_translations for views and controllers

Add the configuration option for annotating templates with file names to the generated app

Clarify versioning strategy in maintenance policy

Not all releases are using `X.Y.Z`.

Since 7b391977, `serializable_hash`
allocates fewer objects when options is nil rather than empty.

Fix index options for if_not_exists/if_exists

The `index_exists?` method wasn't very specific so when we added the
`if_not_exists` to `add_index` and `if_exists` to `remove_index` there
were a few cases where behavior was unexpected.

For `add_index` if you added a named index and then added a second index
with the same columns, but a different name, that index would not get
added because `index_exists` was looking only at column named and not at
the exact index name. We fixed `add_index` by moving the `index_exists`
check below `add_index_options` and pass `name` directly to
`index_exists` if there is a `if_not_exists` option.

For `remove_index` if you added a named index and then tried to remove
it with a nil column and a explicit name the index would not get removed
because `index_exists` saw a nil column. We fixed this by only doing the
column check in `index_exists` if `column` is present.
Co-authored-by: NJohn Crepezzi <john.crepezzi@gmail.com>

Add compact and compact! to ActionController::Parameters

Update aws-sdk-s3 dependency

Update active_record_callbacks.md [ci skip]

Co-authored-by: NJonathan Hefner <jonathan@hefner.pro>

Add DidYouMean for ParameterMissing

Journey is a private API that we want to refactor. We need to stop
calling methods directly on it so we're free to change the
implmentation.

Add DidYouMean for HasManyThroughAssociationNotFoundError

whitelist_headers support added in 1.48.0:
https://github.com/aws/aws-sdk-ruby/blob/master/gems/aws-sdk-s3/CHANGELOG.md#1480-2019-08-30

If a parameter isn't found we can suggest similar params:

```
class BooksController < ActionController::Base
  def create
    params.require(:book).require(:name)
    head :ok
  end
end

post :create, params: { magazine: { name: "Mjallo!" } }

param is missing or the value is empty: book
Did you mean?  controller
               action
               magazine

post :create, params: { book: { title: "Mjallo!" } }

param is missing or the value is empty: name
Did you mean?  title

```

If a has_many :through association isn't found we can suggest similar associations:

```
class Author
  has_many :categorizations, -> { }
  has_many :categories, through: :categorizations
  has_many :categorized_posts, through: :categorizations, source: :post
  has_many :category_post_comments, through: :categories, source: :post_comments

  has_many :nothings, through: :kateggorisatons, class_name: "Category"
end

Author.first.nothings

Could not find the association :kateggorisatons in model Author
Did you mean?  categorizations
               categories
               categorized_posts
               category_post_comments
```