question: @ SuppressWarnings ( "nullness" ) @ GwtIncompatible ( "java.io.ObjectOutputStream" ) public static < K extends Object , V extends Object > void writeMap ( Map < K , V > map , ObjectOutputStream stream ) throws IOException { stream . writeInt ( map . size ( ) ) ; for ( Map . Entry < K , V > entry : map . entrySet ( ) ) { stream . writeObject ( entry . getKey ( ) ) ; stream . writeObject ( entry . getValue ( ) ) ; } }
target:  Stores the contents of a map in an output stream, as part of serialization. It does not support concurrent maps whose content may change while the method is running. <p>The serialized output consists of the number of entries, first key, first value, second key, second value, and so on.