code: public void encodeNullToNull(Writer writer, T obj) throws IOException {
  		if (obj == null) {
  			writer.write("null");
  			return;
  		}
  
  		JsonUtil.startHash(writer);
  
  		encodeValue(writer, obj);
  
  		JsonUtil.endHash(writer);
  
  		writer.flush();
  	}
docs: Encodes the given value into the JSON format, and writes it using the given writer.<br>
  Writes "null" if null is given.
  
  @param writer {@link Writer} to be used for writing value
  @param obj Value to encoded
  @throws IOException