public void removeKey() {
      if( _prevV == null ) throw new IllegalStateException();
      NonBlockingHashMapLong.this.putIfMatch( _prevK, TOMBSTONE, NO_MATCH_OLD);
      _prevV = null;
    }
Auto-boxing version of {@link #replace}.
jctools-core/src/main/java/org/jctools/maps/NonBlockingHashMapLong.java