NodeDefinitionTemplate nodeDef = ntm.createNodeDefinitionTemplate();
nodeDef.setName("child");
nodeDef.setRequiredPrimaryTypeNames(new String[] {"nt:folder"});
nodeDef.setDefaultPrimaryTypeName("nt:folder");
ntd.getNodeDefinitionTemplates().add(nodeDef);
ntm.registerNodeType(ntd, true);
// create node and add mixin
Node node = testRootNode.addNode(nodeName1, "nt:resource");
node.setProperty("jcr:data", "abc");
node.addMixin("testMixin");