Function decode_with 

pub fn decode_with<'a, E, T, R>(
    message: &mut InplaceOption<'_, T>,
    data: &'a [u8],
    resources: &mut [Option<R>],
) -> Result<(), Error>
where
    E: MessageDecode<'a, T, R>,

Decodes a protobuf message into message using encoding T.

If message already exists, then the fields are merged according to protobuf rules.