@Override
  public boolean equals(Object obj) {
    if (obj == null || obj.getClass() != ImmutableByteArray.class) {
      return false;
    }
    return Bytes.equals(b, ((ImmutableByteArray) obj).b);
  }
Mainly used as keys for HashMap.
hbase-common/src/main/java/org/apache/hadoop/hbase/util/ImmutableByteArray.java