Confusing qualifier in "required" line of error message

import org.checkerframework.checker.nullness.qual.Nullable;
import java.util.*;
class Test {
  void foo(Object nn, @Nullable Object nbl) {
      var l = new ArrayList<String>();
      l = new ArrayList<@Nullable String>();
  }
}

When I check the code with the Nullness Checker, I get the error:

Test.java:6: error: [assignment] incompatible types in assignment.
      l = new ArrayList<@Nullable String>();
          ^
  found   : @Initialized @NonNull ArrayList<@Initialized @Nullable String>
  required: @UnknownInitialization @Nullable ArrayList<@Initialized @NonNull String>
1 error

In the "required" line I find @Nullable ArrayList to be confusing. I guess @Nullable is written since it would be ok to assign null here, since we infer the type of local l? The real issue though is that the type argument needs to be @NonNull.

Possibly related to #2276

Start by reproducing the supplied Test.java example with the Nullness Checker and inspect how the assignment diagnostic formats its found and required types. Determine wording that makes the nullable outer type and non-null element type distinction clear, then verify the revised diagnostic with the example.