private void cleanRegionRootDir(final FileSystem fs, final Path dir) throws IOException {
    if (fs.exists(dir)) {
      fs.delete(dir, true);
    }
  }
Verify the content of the WAL file. Verify that the file has expected number of edits.
@param wals may not be null
@return Count of edits.
hbase-diagnostics/src/main/java/org/apache/hadoop/hbase/wal/WALPerformanceEvaluation.java