JavaModuleSourceRoot (@NotNull JavaModuleSourceRoot root) { List<@Nls(capitalization = Nls.Capitalization.Sentence) String> union = new ArrayList<>(myLanguages.size() + root.myLanguages.size()); union.addAll(myLanguages); union.addAll(root.myLanguages); ContainerUtil.removeDuplicates(union); return new JavaModuleSourceRoot(getDirectory(), getPackagePrefix(), union); }