private File getDiskDir() {
    return diskDirRule.getDiskDirFor(getController());
  }
Create a region, installing the test hook in the backup lock

@param shortcut The region shortcut to use to create the region
@return The newly created region.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/backup/PrepareAndFinishBackupDistributedTest.java