Allow to alter the value's format [#3333643]

Right now subscribers can alter the outbound value but there's no way to alter the value's format.

Show commands

Start within a Git clone of the project using the version control instructions.

Add & fetch this issue fork’s repository

Or, if you do not have SSH keys set up on git.drupalcode.org:

Add & fetch this issue fork’s repository

3333643-alter-format changes, plain diff MR !20
Check out this branch for the first time

Check out existing branch, if you already have it locally
3333643-alter-for,at compare
Check out this branch for the first time

Check out existing branch, if you already have it locally