apollo-openapi/src/main/java/com/ctrip/framework/apollo/openapi/dto/OpenEnvClusterDTO.java/OpenEnvClusterDTO/toString
class OpenEnvClusterDTO:  @Override
  public String toString() {
    return "OpenEnvClusterDTO{" +
        "env='" + env + '\'' +
        ", clusters=" + clusters +
        '}';
  }