code: public static String formattingFinishedPercentage(final RolloutGroup rolloutGroup, final float finishedPercentage) {
          float tmpFinishedPercentage = 0;
          switch (rolloutGroup.getStatus()) {
          case READY:
          case SCHEDULED:
          case ERROR:
              tmpFinishedPercentage = 0.0F;
              break;
          case FINISHED:
              tmpFinishedPercentage = 100.0F;
              break;
          case RUNNING:
              tmpFinishedPercentage = finishedPercentage;
              break;
          default:
              break;
          }
          return String.format("%.1f", tmpFinishedPercentage);
      }
docs: Formats the finished percentage of a rollout group into a string with one
  digit after comma.
  
  @param rolloutGroup
  the rollout group
  @param finishedPercentage
  the calculated finished percentage of the rolloutgroup
  @return formatted String value