createMapField<K, V>  method 
    Null safety
- int tagNumber,
- MapFieldInfo<K, V> fi
inherited
    Creates a Map representing a map field.
Implementation
Map<K, V> createMapField<K, V>(int tagNumber, MapFieldInfo<K, V> fi) {
  return PbMap<K, V>(fi.keyFieldType, fi.valueFieldType);
}