code: @Override
  	public void writeTo(T t, CodedOutputStream out) throws IOException {
  		for (FieldInfo fieldInfo : fieldInfos) {
  			Object value = FieldUtils.getField(t, fieldInfo.getField());
  			if (value != null) {
  				writeTo(fieldInfo, value, out);
  			}
  		}
  
  	}
docs: /*
  (non-Javadoc)
  
  @see com.baidu.bjf.remoting.protobuf.Codec#writeTo(java.lang.Object,
  com.google.protobuf.CodedOutputStream)