WP_Customize_Selective_Refresh::add_dynamic_partials

			 *
			 * For a dynamic partial to be registered, this filter must be employed
			 * to override the default false value with an array of args to pass to
			 * the WP_Customize_Partial constructor.
			 *
			 * @since 4.5.0
			 *
			 * @param false|array $partial_args The arguments to the WP_Customize_Partial constructor.
			 * @param string      $partial_id   ID for dynamic partial.
			 */
			$partial_args = apply_filters( 'customize_dynamic_partial_args', $partial_args, $partial_id );
			if ( false === $partial_args ) {
				continue;
			}

			/**
			 * Filters the class used to construct partials.
			 *
			 * Allow non-statically created partials to be constructed with custom WP_Customize_Partial subclass.
			 *
			 * @since 4.5.0
			 *
			 * @param string $partial_class WP_Customize_Partial or a subclass.
			 * @param string $partial_id    ID for dynamic partial.
			 * @param array  $partial_args  The arguments to the WP_Customize_Partial constructor.
			 */
			$partial_class = apply_filters( 'customize_dynamic_partial_class', $partial_class, $partial_id, $partial_args );

			$partial = new $partial_class( $this, $partial_id, $partial_args );

			$this->add_partial( $partial );
			$new_partials[] = $partial;
		}
		return $new_partials;
	}

	/**
	 * Checks whether the request is for rendering partials.
	 *
	 * Note that this will not consider whether the request is authorized or valid,
	 * just that essentially the route is a match.
	 *
	 * @since 4.5.0
	 *
	 * @return bool Whether the request is for rendering partials.
	 */
	public function is_render_partials_request() {
		return ! empty( $_POST[ self::RENDER_QUERY_VAR ] );
	}

	/**