Unsoundness in Nullness Checker with record patterns

Test:

import org.checkerframework.checker.nullness.qual.Nullable;
public class Test {
  sealed interface IntOrBool {}
  public record WrappedInt(Integer a) implements IntOrBool {}
  public record WrappedBoolean(@Nullable Boolean b) implements IntOrBool {}
  public static void test(IntOrBool i) {
    switch (i) {
      case WrappedInt(Integer x) -> {
      }
      case WrappedBoolean(Boolean y) -> {
        y.hashCode();
      }
    }
  }
  public static void main(String[] args) {
    test(new WrappedBoolean(null));
  }
}

We get an NPE at runtime but it's not detected by the nullness checker. If we write case WrappedBoolean(@Nullable Boolean y) an error is reported as expected. Record patterns were finalized in Java 21; not sure if that version is officially supported by the Checker Framework yet.

Start with the supplied Java reproducer and the nullness checker’s handling of record patterns, focusing on why the unannotated Boolean pattern variable is treated as non-null. Compare it with the explicit @Nullable pattern case and verify behavior with Java 21 record patterns. Done means the checker reports the possible null dereference in y.hashCode().