removeGroup method
移除指定分组的所有控制器
Implementation
void removeGroup(String label) {
final group = _groups[label];
if (group != null) {
for (final controller in group) {
_controllerCompletionStatus.remove(controller);
}
_groups.remove(label);
_groupCompletionStatus.remove(label);
_groupCallbacks.remove(label);
_checkAllCompleted();
}
}