Structural interface cannot override method of extending interface

[EotT123]

Describe the bug
A structural interface cannot override a method from an extended interface. Removing the @Structural annotation from the 'child' interface resolves the issue.

@Structural
public interface ParentIntf {
   Object foo();
}

@Structural
public interface ChildIntf extends ParentIntf {
   @Override // ERROR: Method does not override method from its superclass
   default Object foo(){
      return "test";
   }
}

Expected Behavior
The ChildIntf interface should be allowed to override the foo() method from ParentIntf interface without any errors, regardless of the @Structural annotation.

Desktop (please complete the following information):

• OS Type & Version: Windows 10 22H2
• Java/JDK version: openjdk 23.0.1
• IDE version (IntelliJ IDEA or Android Studio): IntelliJ IDEA 2024.3
• Manifold version: 2024.1.42 (latest version)
• Manifold IntelliJ plugin version: 2024.1.13 (latest version)