Added test to ensure that DescendantsTracker does not leak memory on singleton classes
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.
Fixed a bug in  when using has_many association with :inverse_of option and UUID primary key.
DirtyModel uses a hash to keep track of any changes made to attributes
of an instance. When using the attribute_will_change! method, you must
supply a string and not a symbol or the *_changed? method will break
(because it is looking for the attribute name as a string in the keys
of the underlying hash). To remedy this, I simply made the underlying
hash a HashWithIndifferentAccess so it won't matter if you supply
the attribute name as a symbol or string to attribute_will_change!.
make sure both headers are set before checking for ip spoofing
Adding documentation to +polymorphic_url+
concerning the options that it inherits from +url_for+. The way that
+polymorhpic_url+ is built allows it to have options
like +:anchor+, +:script_name+, etc. but this is currently not
documented.
Fix doc in Postgres database creation
Raising an error when nil or non-hash is passed to update_attributes.
Fix typo.
Migration dump UUID default functions to schema.rb. Fixes #10751.
Disable ability to iterate over a Range of TimeWithZone
add active model basics wip to guides/documents.yaml
let the sqlite task run without rails
Remove sqlite specific`supports_autoincrement?` which always defaults to true
Creating options for schema dumper.

These options make it easier to change the config from
ActiveRecord::Base to use something else inside of the SchemaDumper.
Rewrite journey routes formatter for performance
Small refactoring changes to generators.

Made a method name clearer (added a bang to the end to show that it
mutates arguments) and extracted indentation into its own method.
support :unless_exist for FileCache
Fix spacing issue
4.0 Release notes should point to 4.0 Changelog