import java.util.LinkedHashMap; import java.util.Map; import java.util.function.Supplier; import java.util.stream.Collectors; class Test { void m() { // IDEA-337371 -- error reporting still should be improved var o = new MapDropdownChoice( () -> { Map choices = Map.of("id1", 1); return choices.entrySet().stream() .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, LinkedHashMap::new)); }); } static class MapDropdownChoice { public MapDropdownChoice(Supplier> choiceMap) {} } }