public static ServiceSpecification merge(Iterable<ServiceSpecification> specs, Route docServiceRoute) {
        return new ServiceSpecification(
                Streams.stream(specs).flatMap(s -> s.services().stream())::iterator,
                Streams.stream(specs).flatMap(s -> s.enums().stream())::iterator,
                Streams.stream(specs).flatMap(s -> s.structs().stream())::iterator,
                Streams.stream(specs).flatMap(s -> s.exceptions().stream())::iterator,
                ImmutableList.of(),
                docServiceRoute
        );
    }
Merges the specified {@link ServiceSpecification}s into one.
core/src/main/java/com/linecorp/armeria/server/docs/ServiceSpecification.java