interface EntityFormBuilderInterface

interface EntityFormBuilderInterface {
    
    /**
     * Gets the built and processed entity form for the given entity.
     *
     * The form may also be retrieved from the cache if the form was built in a
     * previous page load. The form is then passed on for processing, validation,
     * and submission if there is proper input.
     *
     * @param \Drupal\Core\Entity\EntityInterface $entity
     *   The entity to be created or edited.
     * @param string $operation
     *   (optional) The operation identifying the form variation to be returned.
     *   Defaults to 'default'. This is typically used in routing:
     *   @code
     *   _entity_form: node.book_outline
     *   @endcode
     *   where "book_outline" is the value of $operation. The class name for the
     *   form for each operation (edit, delete, etc.) can be found in the form
     *   section of the handlers entity annotation. For example:
     *   @code
     *   handlers = {
     *     "form" = {
     *       "delete" = "Drupal\node\Form\NodeDeleteForm",
     *   @endcode
     *   Alternatively, the form class can be set from hook_entity_type_build().
     * @param array $form_state_additions
     *   (optional) An associative array used to build the current state of the
     *   form. Use this to pass additional information to the form, such as the
     *   langcode. Defaults to an empty array.
     *
     * @code
     *   $form_state_additions['langcode'] = $langcode;
     *   $form = \Drupal::service('entity.form_builder')->getForm($entity, 'default', $form_state_additions);
     * @endcode
     *
     * @return array
     *   The processed form for the given entity and operation.
     *
     * @see \Drupal\Core\Form\FormBuilderInterface::getForm()
     * @see \Drupal\Core\Entity\EntityTypeInterface::getFormClass()
     * @see \Drupal\Core\Entity\EntityTypeInterface::setFormClass()
     * @see system_entity_type_build()
     */
    public function getForm(EntityInterface $entity, $operation = 'default', array $form_state_additions = []);

}