private File getStatsDir() throws IOException {
    if (statsDir == null) {
      statsDir = tempDir.newFolder("stats");
    }
    return statsDir;
  }
Since these are not visible to cache.diskPerf we add wrapper methods to make the following
parameters/visible
geode-junit/src/main/java/org/apache/geode/internal/cache/DiskRegionTestingBase.java