forkJoin is deprecated: resultSelector is deprecated, pipe to map instead

I was able to fix this by getting rid of the ellipsis:

forkJoin(observables).subscribe();

As long as observables is already an array, it should have the same result.

forkJoin(observable1, observable2)   // WORKING - deprecation warning
(memberObservables) => forkJoin(memberObservables)) // warning, too
forkJoin([observable1, observable2]) // WORKING - no warning
(memberObservables: Array<any>) => forkJoin(memberObservables)) // no warning