@Nullable
    @Override
    public ServerMethodDefinition<?, ?> methodDefinition(ServiceRequestContext ctx) {
        final TranscodingSpec spec = routeAndSpecs.get(ctx.config().mappedRoute());
        if (spec != null) {
            return spec.method;
        }
        return super.methodDefinition(ctx);
    }
Returns the {@link Route}s which are supported by this service and the {@code delegate}.
grpc/src/main/java/com/linecorp/armeria/server/grpc/HttpJsonTranscodingService.java