Problems calling private static methods

class Test { 
  // all errors go away if method is declared non-private 
  private static foo() {} 
  
  static callFooFromStaticMethod() { 
    Test.foo()        // ok 
    foo()             // ok 
    this.foo()        // ok 
    new Test().foo()  // java.lang.IncompatibleClassChangeError 
  } 
  
  def callFooFromInstanceMethod() { 
    Test.foo()       // ok 
    foo()            // java.lang.IncompatibleClassChangeError 
    this.foo()       // java.lang.IncompatibleClassChangeError 
    new Test().foo() // java.lang.IncompatibleClassChangeError 
  } 
} 

Test.callFooFromStaticMethod() 
new Test().callFooFromInstanceMethod()