Should return false but throws ClassCastException.
==== Here is the minimized test demonstrating the bug ====
import java.lang.Bignum;
class java_lang_Bignum_equals {
  public static void main(String args[]) {
    Bignum b=new Bignum(1);
    System.out.println(b.equals("String")); // should print "false"
  }
}
==== Here is the output of the test ====
java.lang.ClassCastException: java.lang.String
at java.lang.Bignum.equals(Bignum.java)
at java_lang_Bignum_equals.main(java_lang_Bignum_equals.java:5)