code: private void addPendingChange(String key, JsonValue value) {
          if (this.pendingChanges == null) {
              this.pendingChanges = new JsonObject();
          }
  
          this.pendingChanges.set(key, value);
      }
docs: Adds a pending field change that needs to be sent to the API. It will be included in the JSON string the next
  time {@link #getPendingChanges} is called.
  @param key   the name of the field.
  @param value the JsonValue of the field.