@Nullable
    private static MethodDescriptor methodDescriptor(ServerMethodDefinition<?, ?> methodDefinition) {
        @Nullable
        final Object desc = methodDefinition.getMethodDescriptor().getSchemaDescriptor();
        if (desc instanceof ProtoMethodDescriptorSupplier) {
            return ((ProtoMethodDescriptorSupplier) desc).getMethodDescriptor();
        }
        return null;
    }
Creates a new {@link GrpcService} instance from the given {@code delegate}. If it is possible
to support HTTP/JSON to gRPC transcoding, a new {@link HttpJsonTranscodingService} instance
would be returned. Otherwise, the {@code delegate} would be returned.
grpc/src/main/java/com/linecorp/armeria/server/grpc/HttpJsonTranscodingService.java