grpc.aio.ServerInterceptor is incompatible with async RPC methods

The grpc.aio.ServerInterceptor is currently annotated using grpc.RpcMethodHandler. However the interface for grpc.RpcMethodHandler is not compatible with async RPC methods. The correct stub for an async version would make use of Awaitable and AsyncIterator:

class RpcMethodHandler(abc.ABC, Generic[_TRequest, _TResponse]):
    request_streaming: bool
    response_streaming: bool

    # XXX: not clear from docs whether this is optional or not
    request_deserializer: _Deserializer[_TRequest] | None

    # XXX: not clear from docs whether this is optional or not
    response_serializer: _Serializer[_TResponse] | None

    unary_unary: Callable[[_TRequest, ServicerContext], Awaitable[_TResponse]] | None

    unary_stream: Callable[[_TRequest, ServicerContext], AsyncIterator[_TResponse]] | None

    stream_unary: Callable[[Iterator[_TRequest], ServicerContext], Awaitable[_TResponse]] | None

    stream_stream: Callable[[Iterator[_TRequest], ServicerContext], AsyncIterator[_TResponse]] | None

Inspecciona stubs/grpcio/grpc/aio/init.pyi alrededor de las líneas 374-383 y compara la anotación del interceptor con la forma de async RpcMethodHandler descrita en el issue. Revisa el pull request abierto #15497; se considera terminado cuando el stub acepta métodos RPC asíncronos que usan Awaitable y AsyncIterator sin entrar en conflicto con la interfaz de handler existente.