WP_REST_Meta_Fields::get_registered_fields

	 * @return bool
	 */
	protected function is_meta_value_same_as_stored_value( $meta_key, $subtype, $stored_value, $user_value ) {
		$args      = $this->get_registered_fields()[ $meta_key ];
		$sanitized = sanitize_meta( $meta_key, $user_value, $this->get_meta_type(), $subtype );

		if ( in_array( $args['type'], array( 'string', 'number', 'integer', 'boolean' ), true ) ) {
			// The return value of get_metadata will always be a string for scalar types.
			$sanitized = (string) $sanitized;
		}

		return $sanitized === $stored_value;
	}

	/**
	 * Retrieves all the registered meta fields.
	 *
	 * @since 4.7.0
	 *
	 * @return array Registered fields.
	 */
	protected function get_registered_fields() {
		$registered = array();

		$meta_type    = $this->get_meta_type();
		$meta_subtype = $this->get_meta_subtype();

		$meta_keys = get_registered_meta_keys( $meta_type );
		if ( ! empty( $meta_subtype ) ) {
			$meta_keys = array_merge( $meta_keys, get_registered_meta_keys( $meta_type, $meta_subtype ) );
		}

		foreach ( $meta_keys as $name => $args ) {
			if ( empty( $args['show_in_rest'] ) ) {
				continue;
			}

			$rest_args = array();

			if ( is_array( $args['show_in_rest'] ) ) {
				$rest_args = $args['show_in_rest'];
			}

			$default_args = array(
				'name'             => $name,
				'single'           => $args['single'],
				'type'             => ! empty( $args['type'] ) ? $args['type'] : null,
				'schema'           => array(),
				'prepare_callback' => array( $this, 'prepare_value' ),
			);

			$default_schema = array(
				'type'        => $default_args['type'],
				'description' => empty( $args['description'] ) ? '' : $args['description'],
				'default'     => isset( $args['default'] ) ? $args['default'] : null,
			);

			$rest_args           = array_merge( $default_args, $rest_args );
			$rest_args['schema'] = array_merge( $default_schema, $rest_args['schema'] );

			$type = ! empty( $rest_args['type'] ) ? $rest_args['type'] : null;
			$type = ! empty( $rest_args['schema']['type'] ) ? $rest_args['schema']['type'] : $type;

			if ( null === $rest_args['schema']['default'] ) {