code: @InterfaceStability.Committed
      public AsyncMutateInBuilder insertDocument(boolean insertDocument) {
          if (this.upsertDocument && insertDocument) {
              throw new IllegalArgumentException("Cannot set both upsertDocument and insertDocument to true");
          }
          this.insertDocument = insertDocument;
          return this;
      }
docs: Set insertDocument to true, if the document has to be created only if it does not exist
  
  @param insertDocument true to insert document.