private static final boolean isInvalid(byte[] key) {
    // No need to use Arrays.equals because INVALID_KEY is null
    return key == INVALID_KEY;
  }
Checks whether the key is invalid (e.g. from an L0 file, or non-stripe-compacted files).
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StripeStoreFileManager.java