@Override
  public RequestStatus deleteResources(Request request, Predicate predicate) throws SystemException,
      UnsupportedPropertyException, NoSuchResourceException, NoSuchParentResourceException {
    throw new SystemException("Cannot delete Upgrades");
  }
Unlike in CalculatedStatus, we can't use ABORTED here as a COMPLETED state.
Therefore, the values will be slightly off since in CalulatedStatus, ABORTED
contributes all of its progress to the overall progress, but here it
contributes none of it.

Since this is specifically for ABORTED upgrades that are
also suspended, the percentages should come out pretty close after ABORTED move back
to PENDING.

@return the percent complete, counting ABORTED as zero percent.
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/UpgradeResourceProvider.java