boolean result = concreteImplementation.isIntermediate();
            assertNotNull(result);
        }

        @Test
        @DisplayName("Should combine referral data")
        void testCombine() {
            DfsReferralDataInternal combined = mock(DfsReferralDataInternal.class);

            // Test with mock
            when(mockReferralData.combine(mockDfsReferralData)).thenReturn(combined);