void ISerializer <TimeSpan> .Write(ref ProtoWriter.State state, TimeSpan value)
 => PrimaryTypeProvider.WriteDuration(ref state, value);
 void ISerializer <DateTime> .Write(ref ProtoWriter.State state, DateTime value)
 => PrimaryTypeProvider.WriteTimestamp(ref state, value);
 TimeSpan ISerializer <TimeSpan> .Read(ref ProtoReader.State state, TimeSpan value)
 => PrimaryTypeProvider.ReadDuration(ref state, value);
 DateTime ISerializer <DateTime> .Read(ref ProtoReader.State state, DateTime value)
 => PrimaryTypeProvider.ReadTimestamp(ref state, value);