apollo-core/src/main/java/com/ctrip/framework/foundation/internals/provider/DefaultServerProvider.java/DefaultServerProvider/toString
class DefaultServerProvider:  @Override
  public String toString() {
    return "environment [" + getEnvType() + "] data center [" + getDataCenter() + "] properties: "
        + m_serverProperties
        + " (DefaultServerProvider)";
  }