public Mono<UpdateResult> updateRelationshipGroups(
            @NotEmpty Set<UserRelationshipGroup.@ValidUserRelationshipGroupKey Key> keys,
            @Nullable String name,
            @Nullable @PastOrPresent Date creationDate) {
        try {
            Validator.notEmpty(keys, "keys");
            for (UserRelationshipGroup.Key key : keys) {
                DataValidator.validRelationshipGroupKey(key);
            }
            Validator.pastOrPresent(creationDate, "creationDate");
        } catch (ResponseException e) {
            return Mono.error(e);
        }
        if (name == null && creationDate == null) {
            return OperationResultPublisherPool.ACKNOWLEDGED_UPDATE_RESULT;
        }
        return userRelationshipGroupRepository.updateRelationshipGroups(keys, name, creationDate);
    }
@return the relationship index only if the related user is added to the group.
turms-service/src/main/java/im/turms/service/domain/user/service/UserRelationshipGroupService.java