question: private void captureDifferentString ( String oldString , String newString , Map < String , String > map , String appName ) { Reject . ifNull ( appName ) ; Reject . ifNull ( map ) ; if ( oldString == null ? newString != null : ! oldString . equals ( newString ) ) { map . put ( appName , newString ) ; } }
target:  Adds entries to the passed in map, using the supplied appName as the key. The value is a new, empty set if both oldSet and newSet are null, or newSet if the contents of oldSet and newSet differ. If the two sets are the same, no entries are added to the map.