### Question:
Message extends StructValue { public Long getMessageId() { return vf.getMessageId( this ); } Message( Type type, ValueFactory vf );  Message( Type type, ValueFactory vf, int length ); ValueFactory vf(); Message reply( Type rType ); Message reply(); Long getMessageId(); void setMessageId( Long msgid ); Long getInReplyTo(); void setInReplyTo( Long msgid );  }### Answer:
@Test public void getMessageId() { Message msg = new Message( mt1, vf ); assertNull( msg.getMessageId() ); msg.setMessageId( 234L ); assertEquals( 234L, msg.getMessageId() ); }