@Override
    public E putIfAbsent(String key, E value) {
        return computeIfAbsent(key, k -> value);
    }
@Test
    public void putIfAbsent_cacheMiss_updatesCache() {
        Function<String, Integer> mappingFunction = k -> 17;
        doReturn(null).when(mutableEntryMock).getValue();
        entryProcessorMock = new CacheRegistryStore.AtomicComputeProcessor<>();
        entryProcessorArgMock = mappingFunction;

        Integer cacheResult = classUnderTest.putIfAbsent(CACHE_KEY, 17);

        verify(mutableEntryMock, times(1)).setValue(17);
        assertEquals(Integer.valueOf(17), cacheResult);
    }