checker/tests/nullness/FinalFields.java

import org.checkerframework.checker.nullness.qual.Nullable;

class Upper {
  @Nullable String fs = "NonNull init";
  final @Nullable String ffs = "NonNull init";

  void access() {
    // Error, because non-final field type is not refined
    // :: error: (dereference.of.nullable)
    fs.hashCode();
    // Final field in the same class is refined
    ffs.hashCode();
  }
}

public class FinalFields {
  public void foo(Upper u) {
    // Error, because final field in different class is not refined
    // :: error: (dereference.of.nullable)
    u.fs.hashCode();
  }

  public void bar(Lower l) {
    // Error, because final field in different class is not refined
    // :: error: (dereference.of.nullable)
    l.fs.hashCode();
  }

  public void local() {
    @Nullable String ls = "Locals";
    // Local variable is refined
    ls.hashCode();
  }
}

class Lower {
  @Nullable String fs = "NonNull init, too";
  final @Nullable String ffs = "NonNull init, too";

  void access() {
    // Error, because non-final field type is not refined
    // :: error: (dereference.of.nullable)
    fs.hashCode();
    // Final field in the same class is refined
    ffs.hashCode();
  }
}