WP_REST_Meta_Fields::register_field

	public function register_field() {
		register_rest_field(
			$this->get_rest_field_type(),
			'meta',
			array(
				'get_callback'    => array( $this, 'get_value' ),
				'update_callback' => array( $this, 'update_value' ),
				'schema'          => $this->get_field_schema(),
			)
		);
	}