@Override
  public @NotNull PrefixMatcher itemMatcher(@NotNull LookupElement item) {
    PrefixMatcher matcher = item.getUserData(myMatcherKey);
    if (matcher == null) {
      throw new AssertionError("Item not in lookup: item=" + item + "; lookup items=" + myItems);
    }
    return matcher;
  }
@Override
  public @NotNull PrefixMatcher itemMatcher(@NotNull LookupElement item)