question: protected static Long max ( Long l1 , Long l2 ) { if ( l1 == null && l2 == null ) { return null ; } if ( l2 == null ) { return l1 ; } if ( l1 == null ) { return l2 ; } return Math . max ( l1 , l2 ) ; }
target:  Utility method to return the maximum of two Long values, either of which may be null.