code: public String serialize( T value, JsonSerializationContext ctx ) throws JsonSerializationException {
          if ( null == value ) {
              return null;
          }
          return doSerialize( value, ctx );
      }
docs: Serializes an object into a {@link String} to use as map's key.
  
  @param value Object to serialize
  @param ctx Context for the full serialization process
  @return the key
  @throws com.github.nmorel.gwtjackson.client.exception.JsonSerializationException if an error occurs during the serialization