import java.util.stream.Collectors; import java.util.stream.Stream; class Test { public static void processDifference(final Stream<String> stream, final Stream<String> cells) { stream.map(rule -> { try { return cells.collect(Collectors.toMap(c -> c, null)); } finally { System.out.println(<error descr="')' expected"><error descr="Expression expected">;</error></error><error descr="Unexpected token">)</error>; } }); } }