private Set<Method> findAnnotatedMethods() {
        return this.annotatedBeans.values().stream()
                .map(Object::getClass)
                .map(this::findAnnotatedMethods)
                .flatMap(Collection::stream)
                .collect(Collectors.toSet());
    }
A filter for selecting {@code @GrpcExceptionHandler} methods.
grpc-server-spring-boot-starter/src/main/java/net/devh/boot/grpc/server/advice/GrpcAdviceDiscoverer.java