public byte[] getEncryptionKey() {
    // This is a v3 feature but if reading a v2 file the encryptionKey will just be null which
    // if fine for this feature.
    expectAtLeastMajorVersion(2);
    return encryptionKey;
  }
Returns the minor version of this HFile format
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/FixedFileTrailer.java