ConfigChangedEvent extends EventObject { @Override public String toString() { return "ConfigChangedEvent{" + "key='" + key + '\'' + ", group='" + group + '\'' + ", content='" + content + '\'' + ", changeType=" + changeType + "} " + super.toString(); } ConfigChangedEvent(String key, String group, String content);  ConfigChangedEvent(String key, String group, String content, ConfigChangeType changeType); String getKey(); String getGroup(); String getContent(); ConfigChangeType getChangeType(); @Override String toString(); @Override boolean equals(Object o); @Override int hashCode();  }
@Test public void testToString() { ConfigChangedEvent event = new ConfigChangedEvent(key, group, content); assertNotNull(event.toString()); }