public void validateDocumentGraph(List<SDDocumentType> documents) {
        for (SDDocumentType document : documents) {
            validateRoot(document);
        }
    }
@Test
    void simple_inheritance_dag_is_allowed() {
        Schema grandfather = createSearchWithName("grandfather");
        Schema father = createSearchWithName("father", grandfather);
        Schema son = createSearchWithName("son", father);

        DocumentGraphValidator validator = new DocumentGraphValidator();
        validator.validateDocumentGraph(documentListOf(son, father, grandfather));
    }