Exception while evaluating classes with static toString() methods

Try the following script:

assert 'class java.text.SimpleDateFormat' == java.text.SimpleDateFormat.toString()
assert 'class java.lang.Integer' == java.lang.Integer.toString()

the second statement throws exception:
Exception thrown: Could not find which method toString() to invoke from this list:
public static java.lang.String java.lang.Integer#toString(int)
public static java.lang.String java.lang.Integer#toString(int, int)

It looks like Class.toString() is not taken into account while trying to evaluate this expression.
Integer.class.toString() produces the same error.