ConfigEntityType inherited functions return FALSE instead of NULL

Problem/Motivation

In ConfigEntityType.php:

  /**
   * {@inheritdoc}
   */
  public function getBaseTable() {
    return FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function getRevisionDataTable() {
    return FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function getRevisionTable() {
    return FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function getDataTable() {
    return FALSE;
  }

Whereas in EntityTypeInterface, each function says:

   * @return string|null
   *   The name of the entity type's revision table, or NULL if none exists.

Proposed resolution

Return NULL instead, or update the phpdoc comments.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet