question: private void writeObject ( java . io . ObjectOutputStream s ) throws java . io . IOException { s . defaultWriteObject ( ) ; for ( Node < K , V > n = findFirst ( ) ; n != null ; n = n . next ) { V v = n . getValidValue ( ) ; if ( v != null ) { s . writeObject ( n . key ) ; s . writeObject ( v ) ; } } s . writeObject ( null ) ; }
target:  Save the state of this map to a stream.