code: public OperationFuture<List<Server>> createSnapshot(Integer expirationDays, Group... groups) {
          return serverService().createSnapshot(
              expirationDays,
              getServerSearchCriteria(groups)
          );
      }
docs: Create snapshot of servers groups
  
  @param expirationDays expiration days (must be between 1 and 10)
  @param groups groups references list
  @return OperationFuture wrapper for Server list