if ( 'term_taxonomy_id' !== $query['field'] ) {
				$query = new WP_Error( 'invalid_taxonomy', __( 'Invalid taxonomy.' ) );
				return;
			}

			// So long as there are shared terms, 'include_children' requires that a taxonomy is set.
			$query['include_children'] = false;
		} elseif ( ! taxonomy_exists( $query['taxonomy'] ) ) {
			$query = new WP_Error( 'invalid_taxonomy', __( 'Invalid taxonomy.' ) );
			return;
		}

		if ( 'slug' === $query['field'] || 'name' === $query['field'] ) {
			$query['terms'] = array_unique( (array) $query['terms'] );
		} else {
			$query['terms'] = wp_parse_id_list( $query['terms'] );
		}

		if ( is_taxonomy_hierarchical( $query['taxonomy'] ) && $query['include_children'] ) {
			$this->transform_query( $query, 'term_id' );

			if ( is_wp_error( $query ) ) {
				return;
			}

			$children = array();
			foreach ( $query['terms'] as $term ) {
				$children   = array_merge( $children, get_term_children( $term, $query['taxonomy'] ) );
				$children[] = $term;
			}
			$query['terms'] = $children;
		}

		$this->transform_query( $query, 'term_taxonomy_id' );
	}

	/**
	 * Transforms a single query, from one field to another.
	 *
	 * Operates on the `$query` object by reference. In the case of error,
	 * `$query` is converted to a WP_Error object.
	 *
	 * @since 3.2.0
	 *
	 * @param array  $query           The single query. Passed by reference.
	 * @param string $resulting_field The resulting field. Accepts 'slug', 'name', 'term_taxonomy_id',
	 *                                or 'term_id'. Default 'term_id'.
	 */
	public function transform_query( &$query, $resulting_field ) {
		if ( empty( $query['terms'] ) ) {
			return;
		}

		if ( $query['field'] === $resulting_field ) {
			return;
		}

		$resulting_field = sanitize_key( $resulting_field );

		// Empty 'terms' always results in a null transformation.
		$terms = array_filter( $query['terms'] );
		if ( empty( $terms ) ) {
			$query['terms'] = array();
			$query['field'] = $resulting_field;
			return;
		}

		$args = array(
			'get'                    => 'all',
			'number'                 => 0,
			'taxonomy'               => $query['taxonomy'],
			'update_term_meta_cache' => false,
			'orderby'                => 'none',
		);

		// Term query parameter name depends on the 'field' being searched on.
		switch ( $query['field'] ) {
			case 'slug':
				$args['slug'] = $terms;
				break;
			case 'name':
				$args['name'] = $terms;
				break;
			case 'term_taxonomy_id':
				$args['term_taxonomy_id'] = $terms;
				break;
			default:
				$args['include'] = wp_parse_id_list( $terms );
				break;
		}

		if ( ! is_taxonomy_hierarchical( $query['taxonomy'] ) ) {
			$args['number'] = count( $terms );
		}

		$term_query = new WP_Term_Query();
		$term_list  = $term_query->query( $args );

		if ( is_wp_error( $term_list ) ) {
			$query = $term_list;
			return;
		}

		if ( 'AND' === $query['operator'] && count( $term_list ) < count( $query['terms'] ) ) {
			$query = new WP_Error( 'inexistent_terms', __( 'Inexistent terms.' ) );
			return;
		}

		$query['terms'] = wp_list_pluck( $term_list, $resulting_field );
		$query['field'] = $resulting_field;
	}
}
tize_value_from_schema( $value, $schema );
	}

	/**
	 * Check the 'meta' value of a request is an associative array.
	 *
	 * @since 4.7.0
	 *
	 * @param mixed           $value   The meta value submitted in the request.
	 * @param WP_REST_Request $request Full details about the request.
	 * @param string          $param   The parameter name.
	 * @return array|false The meta array, if valid, false otherwise.
	 */
	public function check_meta_is_array( $value, $request, $param ) {
		if ( ! is_array( $value ) ) {
			return false;
		}

		return $value;
	}

	/**
	 * Recursively add additionalProperties = false to all objects in a schema if no additionalProperties setting
	 * is specified.
	 *
	 * This is needed to restrict properties of objects in meta values to only
	 * registered items, as the REST API will allow additional properties by
	 * default.
	 *
	 * @since 5.3.0
	 * @deprecated 5.6.0 Use rest_default_additional_properties_to_false() instead.
	 *
	 * @param array $schema The schema array.
	 * @return array
	 */
	protected function default_additional_properties_to_false( $schema ) {
		_deprecated_function( __METHOD__, '5.6.0', 'rest_default_additional_properties_to_false()' );

		return rest_default_additional_properties_to_false( $schema );
	}

	/**
	 * Gets the empty value for a schema type.
	 *
	 * @since 5.3.0
	 *
	 * @param string $type The schema type.
	 * @return mixed
	 */
	protected static function get_empty_value_for_type( $type ) {
		switch ( $type ) {
			case 'string':
				return '';
			case 'boolean':
				return false;
			case 'integer':
				return 0;
			case 'number':
				return 0.0;
			case 'array':
			case 'object':
				return array();
			default:
				return null;
		}
	}
}