@NotNull
  protected LookupElement installInsertHandler(@NotNull LookupElementBuilder builder) {
    InsertHandler<LookupElement> handler = builder.getInsertHandler();
    if (handler == null) return builder.withInsertHandler(myInsertHandler);
    return builder.withInsertHandler(new InsertHandler<>() {
      @Override
      public void handleInsert(@NotNull InsertionContext context, @NotNull LookupElement item) {
        myInsertHandler.handleInsert(context, item);
        handler.handleInsert(context, item);
      }
    });
  }
@NotNull
  protected LookupElement installInsertHandler(@NotNull LookupElementBuilder builder)