question: public static void assertEquals ( String message , Set < ? extends Object > expected , Set < ? extends Object > actual ) { Set < Object > onlyInExpected = new HashSet < Object > ( expected ) ; onlyInExpected . removeAll ( actual ) ; Set < Object > onlyInActual = new HashSet < Object > ( actual ) ; onlyInActual . removeAll ( expected ) ; if ( onlyInExpected . size ( ) != 0 || onlyInActual . size ( ) != 0 ) { Set < Object > intersection = new HashSet < Object > ( expected ) ; intersection . retainAll ( actual ) ; failWithMessage ( message , "Sets do not match.\nOnly in expected: " + onlyInExpected + "\nOnly in actual: " + onlyInActual + "\nIntersection: " + intersection ) ; } }
target:  Asserts that two sets contain the same elements. 