ConfigFormBaseTrait::config() @return doxygen is inaccurate

Thanks!

+++ b/core/lib/Drupal/Core/Form/ConfigFormBaseTrait.php
@@ -41,8 +41,10 @@
-   * @return \Drupal\Core\Config\Config|\Drupal\Core\Config\ImmutableConfig
-   *   A configuration object.
+   * @return \Drupal\Core\Config\Config|\Drupal\Core\Config\Config|\Drupal\Core\Config\ImmutableConfig
+   *   An editable configuration object if the given name is listed in the
+   *   getEditableConfigNames() method or an immutable configuration object if
+   *   not.

Um...

So it looks like the @return line already has both Config and ImmutableConfig in it. The new @return line in the patch has added Config in there twice?

I like the added docs, because they clarify when each one will be returned, but the changes to @return line itself seem to be wrong.

Also... Do you think we could fix up this paragraph that is further up in the docs header?

   * Objects that use the trait need to implement the
   * \Drupal\Core\Form\ConfigFormBaseTrait::getEditableConfigNames() to declare
   * which configuration objects this method returns override free and mutable.
   * This ensures that overrides do not pollute saved configuration.
 

I cannot understand what it means. Actually, it seems like the docs you have added to @return kind of restate this. So maybe just take this out?

Looks good, thanks!

This should be OK for 8.0, 8.1, and 8.2. I'll set this to 8.2 with backport tags, and set off a test against 8.2.

Committed ea35e64 and pushed to 8.0.x, 8.1.x, and 8.2.x. Thanks!