@NotNull
  Map<FileNameMatcher, T> getRemovedMappings(@NotNull FileTypeAssocTable<T> newTable, @NotNull Collection<? extends T> keys) {
    Map<FileNameMatcher, T> map = new HashMap<>();
    for (T key : keys) {
      List<FileNameMatcher> associations = getAssociations(key);
      associations.removeAll(newTable.getAssociations(key));
      for (FileNameMatcher matcher : associations) {
        map.put(matcher, key);
      }
    }
    return map;
  }
@NotNull
  Map<FileNameMatcher, T> getRemovedMappings(@NotNull FileTypeAssocTable<T> newTable, @NotNull Collection<? extends T> keys)