### Question:
PlainMailboxManager implements MailboxManager { public void transportControl( Object control, Object value ) throws Exception { transport.transportControl( control, value ); } PlainMailboxManager( TransportMessage transport, String uri,
		Resources resources );  PlainMailboxManager( TransportMessage transport, URL uri,
		Resources resources ); TransportMessage getTransport(); @Override String toString(); boolean sessionMessage( Who sender, Message msg ); void transportMessage( Who recipient, Message msg ); Mailbox transportCall( Who recipient, Message msg ); void register( Mailbox mb ); void unregister( Mailbox mb ); Mailbox getMailbox( Long msgid ); void redeliver( Who sender, Message msg ); int size(); Object sessionQuery( Object query ); void sessionControl( Object control, Object value ); void sessionNotify( Object event ); Object transportQuery( Object query ); void transportControl( Object control, Object value ); void transportNotify( Object event ); SessionMessage getSession(); void setSession( SessionMessage session );  }### Answer:
@Test public void transportControl() throws Exception { Object CONTROL = "foo"; Object VALUE = "bar"; assertNull( transport.what ); assertNull( transport.control ); assertNull( transport.value ); mmgr.transportControl( CONTROL, VALUE ); assertSame( What.TRANSPORT_CONTROL, transport.what ); assertSame( CONTROL, transport.control ); assertSame( VALUE, transport.value ); }