token,
        )
    }
    add(FirErrors.SUBCLASS_OPT_IN_INAPPLICABLE) { firDiagnostic ->
        SubclassOptInInapplicableImpl(
            firDiagnostic.a,
            firDiagnostic as KtPsiDiagnostic,
            token,
        )
    }
    add(FirErrors.SUBCLASS_OPT_ARGUMENT_IS_NOT_MARKER) { firDiagnostic ->
        SubclassOptArgumentIsNotMarkerImpl(

   */
  public static <K extends @Nullable Object, V extends @Nullable Object> SortedMap<K, V> filterKeys(
      SortedMap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
    // TODO(lowasser): Return a subclass of Maps.FilteredKeyMap for slightly better
    // performance.
    return filterEntries(unfiltered, Maps.<K>keyPredicateOnEntries(keyPredicate));
  }

  /**