NestJS: wrap 3rd party decorator & setMetaData in order to use Reflector to check annotation - nestjs

Question

I am using NestJS to implement a project with TypeScript.
I am using a 3rd party library which provide a decorator called Protected, I can use the decorator to annotate my controller method:
#Protected()
myFunc(){
...
}
I have a Guard, in which I want to check whether the annotation is there inside my MyGuard class. I tried:
#Injectable()
export class MyGuard implements CanActivate {
constructor(private reflector: Reflector) {}
canActivate(context: ExecutionContext): Promise<boolean> {
const value = this.reflector.get('Protected', context.getHandler());
console.log(`VALUE: ${metaValue}`);
...
}
}
The log message shows me VALUE: undefined. I read the NestJS doc, there is an example of using setMetadata() and then in Guard method use the metadata key to retrieve metadata to check if the annotation is there. However, this is a 3rd party decorator, there is no information for me whether they use any metadata key.
So, I come up with a workaround, I create my own custom decorator which wraps the 3rd party Protected decorator & use my decorator instead on controller method:
import {Protected} from '3rd-party-lib'
import { SetMetadata } from '#nestjs/common';
export const MyProtected = () => {
Protected();
SetMetadata(IS_PROTECTED, true);
}
But now, the annotation on controller method raises error:
/**
ERROR: Unable to resolve signature of method decorator when called as an expression.
This expression is not callable.
Type 'void' has no call signatures.ts(1241)
**/
#MyProtected()
myFunc(){
...
}
My questions:
Is there a way to use Reflector to check whether the 3rd party annotation is presented in the controller method inside MyGuard ?
If there is no way without using setMetadata & since I don't know what metadata key to check due to 3rd party library. How can I setMetadata myself in my custom decorator in order to achieve what I need?

Answer 1

Why not use Nest's applyDecorators so you can compose the decorator out of several decorators?
export const MyProtected = () => applyDecorators(
Protected(),
SetMetadata(IS_PROTECTED, true)
);