apollo-openapi/src/main/java/com/ctrip/framework/apollo/openapi/client/service/AppOpenApiService.java/AppOpenApiService/getEnvClusterInfo
class AppOpenApiService:  @Override
  public List<OpenEnvClusterDTO> getEnvClusterInfo(String appId) {
    checkNotEmpty(appId, "App id");

    OpenApiPathBuilder pathBuilder = OpenApiPathBuilder.newBuilder()
        .appsPathVal(appId)
        .customResource("envclusters");

    try (CloseableHttpResponse response = get(pathBuilder)) {
      return gson.fromJson(EntityUtils.toString(response.getEntity()), OPEN_ENV_CLUSTER_DTO_LIST_TYPE);
    } catch (Throwable ex) {
      throw new RuntimeException(String.format("Load env cluster information for appId: %s failed", appId), ex);
    }
  }