Cast "oneOf" value to a single value when converting to dict/JSON

I am currently consuming metrics exposed by an OpenTelemetry agent, but when I try to convert the Protobuf metrics to JSON, the "oneOf" occurences are being translated to a dict instead of a single value. Is there any way to change this behavior to only display a single string value?

An example of what is happening:

The proto definitions (the original .proto files can be found here):

syntax = "proto3";

message AnyValue {
  oneof value {
    string string_value = 1;
    bool bool_value = 2;
    int64 int_value = 3;
    double double_value = 4;
    ArrayValue array_value = 5;
    KeyValueList kvlist_value = 6;
    bytes bytes_value = 7;
  }
}

message ArrayValue {
  repeated AnyValue values = 1;
}

message KeyValueList {
  repeated KeyValue values = 1;
}

message KeyValue {
  string key = 1;
  AnyValue value = 2;
}

The dataclasses generated:

@dataclass
class KeyValue(betterproto.Message):
    key: str = betterproto.string_field(1)
    value: "AnyValue" = betterproto.message_field(2)

@dataclass
class AnyValue(betterproto.Message):
    string_value: str = betterproto.string_field(1, group="value")
    bool_value: bool = betterproto.bool_field(2, group="value")
    int_value: int = betterproto.int64_field(3, group="value")
    double_value: float = betterproto.double_field(4, group="value")
    array_value: "ArrayValue" = betterproto.message_field(5, group="value")
    kvlist_value: "KeyValueList" = betterproto.message_field(6, group="value")
    bytes_value: bytes = betterproto.bytes_field(7, group="value")

The current conversion:

{"key": "process.pid", "value": {"intValue": "275"}}

What I would like to have:

{"key": "process.pid", "value": "275"}

No se especifica ningún archivo del repositorio ni ninguna prueba. Empieza reproduciendo la conversión dict/JSON para las clases AnyValue y KeyValue generadas y, después, sigue cómo se serializan los grupos oneof. El trabajo estará terminado cuando los valores escalares oneof produzcan el valor único solicitado, preservando al mismo tiempo el tratamiento adecuado de las variantes message, array, map y bytes.