sortBindingGroups() {

		const bindingsGroups = this.getBindings();

		bindingsGroups.sort( ( a, b ) => ( a.bindings[ 0 ].groupNode.order - b.bindings[ 0 ].groupNode.order ) );

		for ( let i = 0; i < bindingsGroups.length; i ++ ) {

			const bindingGroup = bindingsGroups[ i ];
			this.bindingsIndexes[ bindingGroup.name ].group = i;

			bindingGroup.index = i;

		}

	}
Sorts the bind groups and updates {@link NodeBuilder#bindingsIndexes}.