Unused variable $a in \Drupal\taxonomy\Plugin\Validation\Constraint\TaxonomyTermHierarchyConstraintValidator::validate()

Problem/Motivation

public function validate($entity, Constraint $constraint) {
    $term_storage = $this->entityTypeManager->getStorage($entity->getEntityTypeId());
    assert($term_storage instanceof TermStorageInterface);

    // Newly created entities should be able to specify a parent.
    if ($entity && $entity->isNew()) {
      return;
    }

    $is_pending_revision = !$entity->isDefaultRevision();
    $pending_term_ids = $term_storage->getTermIdsWithPendingRevisions();
    $ancestors = $term_storage->loadAllParents($entity->id());
    $ancestor_is_pending_revision = (bool) array_intersect_key($ancestors, array_flip($pending_term_ids));

    $new_parents = array_column($entity->parent->getValue(), 'target_id');
    $original_parents = array_keys($term_storage->loadParents($entity->id())) ?: [0];
    if (($is_pending_revision || $ancestor_is_pending_revision) && $new_parents != $original_parents) {
      $a = 1;
      $this->context->buildViolation($constraint->message)
        ->atPath('parent')
        ->addViolation();
    }

    $original = $term_storage->loadUnchanged($entity->id());
    if (($is_pending_revision || $ancestor_is_pending_revision) && !$entity->weight->equals($original->weight)) {
      $this->context->buildViolation($constraint->message)
        ->atPath('weight')
        ->addViolation();
    }
  }

$a = 1; is one-line debug code. introduced in #2880149: Convert taxonomy terms to be revisionable, see the commit

Proposed resolution

Remove it.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet