assertDoesNotThrow(() -> concreteImplementation.setCacheMap(null));
        }

        @Test
        @DisplayName("Should handle null in combine")
        void testCombineWithNull() {
            // Test with mock
            when(mockReferralData.combine(null)).thenReturn(mockReferralData);
            DfsReferralDataInternal result = mockReferralData.combine(null);