src/main/java/io/reactivex/plugins/RxJavaPlugins.java
@NonNull
    static Scheduler callRequireNonNull(@NonNull Callable<Scheduler> s) {
        try {
            return ObjectHelper.requireNonNull(s.call(), "Scheduler Callable result can't be null");
        } catch (Throwable ex) {
            throw ExceptionHelper.wrapOrThrow(ex);
        }
    }
@NonNull
    static Scheduler callRequireNonNull(@NonNull Callable<Scheduler> s) {
        try {
            return ObjectHelper.requireNonNull(s.call(), "Scheduler Callable result can't be null");
        } catch (Throwable ex) {
            throw ExceptionHelper.wrapOrThrow(ex);
        }
    }
Wraps the call to the Scheduler creation callable in try-catch and propagates thrown
checked exceptions as RuntimeException and enforces that result is not null.
@param s the {@link Callable} which returns a {@link Scheduler}, not null (not verified). Cannot return null
@return the result of the callable call, not null
@throws NullPointerException if the callable parameter returns null