Ok, having a look to the TypeMapper class of WSC, I found that there is an obvious error when a generated from wsdl tooling API method tries to cast Object which is actually an Object[] to int[]. So I changed these lines in TypeMapper.readArray():

    Object array = Array.newInstance(component, results.size());
    Object arrayResult = results.toArray((Object[]) array);

To:

    Object arrayResult;
    if(component == int.class) {
		int[] inn = new int[results.size()];
		for(int i = 0; i<results.size(); i++){
			inn[i] = ((Integer)results.get(i)).intValue();
		}
		arrayResult = (Object) inn;
	} else {
        Object array = Array.newInstance(component, results.size());
		arrayResult = results.toArray((Object[]) array);
	}
And it solved the issue. If this will not cause any issues later I will commit it to WSC repo.