void (@NotNull YAMLKeyValue keyValue, @NotNull ProblemsHolder problemsHolder) { List<ProblemsHolder> allProblems = allProblemsOrEmpty(problemsHolder, listNonScalarSubTypes(), (nextType, nextHolder) -> nextType.validateKey(keyValue, nextHolder)); allProblems.stream() .flatMap(h -> h.getResults().stream()) .forEach(problemsHolder::registerProblem); }