@file is not required for classes, interfaces and traits

Problem/Motivation

The proposal to relax the @file standard for autoloaded files ie classes, traits and interfaces is approved (see #2304909: Relax requirement for @file when using OO Class or Interface per file) and the Coder already introduced rules for checking the codebase (see #2665744: @file is not required for classes, interfaces and traits).

While Drupal core is waiting for 8.1.0-RC1 to cleanup, there's no reason not to do that for this module which is still in RC.

Proposed resolution

Remove no longer needed @file docblocks from the codebase.

Remaining tasks

Write patch.