apollo-common/src/main/java/com/ctrip/framework/apollo/common/utils/GrayReleaseRuleItemTransformer.java/GrayReleaseRuleItemTransformer/batchTransformFromJSON
class GrayReleaseRuleItemTransformer:  public static Set<GrayReleaseRuleItemDTO> batchTransformFromJSON(String content) {
    return gson.fromJson(content, grayReleaseRuleItemsType);
  }