code: @SuppressWarnings({"unchecked", "rawtypes"})
      public void addField(String key, Object value)
      {
          if (this.body == null || Map.class.isAssignableFrom(this.body.getClass()) == false)
          {
              this.body = Maps.newLinkedHashMap();
          }
  
          ((Map) this.body).put(key, value);
      }
docs: Add field to message body.
  
  @param key key
  @param value value