graph.set(JcrLexicon.PRIMARY_TYPE.getString(registry)).on("/a").to(JcrNtLexicon.BASE.getString(registry));
Node rootNode = session.getRootNode();
Node nodeA = rootNode.getNode("a");
assertThat(nodeA.canAddMixin(MIXIN_TYPE_WITH_AUTO_CHILD.getString(registry)), is(true));
nodeA.addMixin(MIXIN_TYPE_WITH_AUTO_CHILD.getString(registry));
Node childNode = nodeA.getNode(CHILD_NODE_B.getString(registry));
assertThat(childNode, is(notNullValue()));
assertThat(childNode.getPrimaryNodeType().getName(), is(JcrNtLexicon.UNSTRUCTURED.getString(registry)));