### Question:
ProductInfo { public static ProductInfo getInstance() { return ProductInfoHolder.productInfo; } protected  ProductInfo(String version, String groupId, String artifactId); String getName(); String getVersion(); String getGroupId(); String getArtifactId(); static ProductInfo getInstance(); static void main(String[] args);  }### Answer:
@Test public void testGetInstance() throws Exception { ProductInfo info = ProductInfo.getInstance(); assertEquals("S2JDBC-Gen", info.getName()); assertEquals("test-0.0.1", info.getVersion()); assertEquals("test-org.seasar.container", info.getGroupId()); assertEquals("test-s2jdbc-gen", info.getArtifactId()); }