Description Stephan Herrmann 2016-05-06 11:05:37 EDT

+++ This bug was initially created as a clone of Bug #488495 +++

Using Eclipse 4.6-I20160223-0800

After using a few stream methods, it seems that the null constraints get lost. For example, in this code:

@NonNullByDefault
public class Main {

    public static void main(String[] args, Set<String> set) {
        Optional<@Nullable String> kam = set.stream()
                .map(trace -> getString(String.class))
                .findFirst(); // Null type safety (type annotations): The expression of type 'Optional<String>' needs unchecked conversion to conform to 'Optional<@Nullable String>'
        System.out.println(kam);
    }

    public @Nullable static <T extends CharSequence> T getString(Class<T> moduleClass) {
        return null;
    }
}

After the map, it should be a stream of @Nullable String but instead it's just String (can be verified with hover). Because of that, findFirst returns an Optional<String> instead of Optional<@Nullable String>

I attached a sample project for convenience.