public void setRevertAllowed(boolean revertable) {
    revertAllowed = (!revertable ? (short) 0 : (short) 1);
  }
Sets whether this upgrade supports being reverted. This should only ever be
called from the finalization of an upgrade. {@link RepositoryType#MAINT} or
{@link RepositoryType#PATCH} upgrades can be revereted only if they have
not previously been downgraded.

@param revertable
         {@code true} to mark this as being revertable, {@code false}
         otherwise.
ambari-server/src/main/java/org/apache/ambari/server/orm/entities/UpgradeEntity.java