@Test
    void require_that_document_types_with_references_are_topologically_sorted() throws Exception {
        ProtonConfig cfg = getProtonConfig(createClusterWithThreeDocumentTypes());
        assertEquals(3, cfg.documentdb().size());
        assertDocumentDb("c", true, cfg.documentdb(0));
        assertDocumentDb("b", true, cfg.documentdb(1));
        assertDocumentDb("a", false, cfg.documentdb(2));
    }
Unit tests for content search cluster.

@author geirst
config-model/src/test/java/com/yahoo/vespa/model/content/ContentSchemaClusterTest.java