question: protected Set < TUConstraint > afToTuConstraints ( Set < ? extends AFConstraint > afConstraints , Set < TypeVariable > targets ) { final Set < TUConstraint > outgoing = new LinkedHashSet < > ( ) ; for ( final AFConstraint afConstraint : afConstraints ) { if ( ! afConstraint . isIrreducible ( targets ) ) { ErrorReporter . errorAbort ( "All afConstraints should be irreducible before conversion.\n" + "afConstraints=[ " + PluginUtil . join ( ", " , afConstraints ) + " ]\n" + "targets=[ " + PluginUtil . join ( ", " , targets ) + "]" ) ; } outgoing . add ( afConstraint . toTUConstraint ( ) ) ; } return outgoing ; }
target:  Convert AFConstraints to TUConstraints