How to read ora_java.object

I find myself with the following inconvenience: a client jar for a webService, this will be integrated with oracle forms through a library.pll

When importing java class I care about the following data type:

  -- Method: getPCODRES ()Ljava/math/BigInteger;
  FUNCTION getPCODRES(
    obj   ORA_JAVA.JOBJECT) RETURN ORA_JAVA.JOBJECT IS
  BEGIN
    args := NULL;
    RETURN JNI.CALL_OBJECT_METHOD(FALSE, obj, 'com/anulapedidos/Anular', 'getCODIGO', '()Ljava/math/BigInteger;', args); 
  END;

Is there a way to read what returns ?, I should compare it with a number.

In the java class the attribute Codigo is defined as BigInteger , and the same class is armed with the import of the wsdl .

Greetings.