question: protected void addConnection ( final Territory t1 , final Territory t2 ) { if ( t1 . equals ( t2 ) ) { throw new IllegalArgumentException ( "Cannot connect a territory to itself" ) ; } if ( ! m_territories . contains ( t1 ) || ! m_territories . contains ( t2 ) ) { throw new IllegalArgumentException ( "Map doesnt know about one of " + t1 + " " + t2 ) ; } setConnection ( t1 , t2 ) ; setConnection ( t2 , t1 ) ; }
target:  Bi-directional. T1 connects to T2, and T2 connects to T1.