// test that it consistently returns null for any input
        assertNull(invokeMethod(provider, "findOnMainSchema", "TestClassification"));
        assertNull(invokeMethod(provider, "findOnMainSchema", ""));
        assertNull(invokeMethod(provider, "findOnMainSchema", "Some.Classification"));
        assertNull(invokeMethod(provider, "findOnMainSchema", "Project.TestClassification"));
    }

        field.setAccessible(true);
        return field.get(obj);
    }

    /**
     * Helper method to invoke protected/private method using reflection
     */
    private Object invokeMethod(Object obj, String methodName, Class<?>[] paramTypes, Object... args) throws Exception {
        Method method = obj.getClass().getDeclaredMethod(methodName, paramTypes);
        method.setAccessible(true);