public ValueCollection values()
    {
        if (null == valueCollection)
        {
            valueCollection = new ValueCollection();
        }

        return valueCollection;
    }
@Test
    void removeIfOnValuesCollection()
    {
        final Predicate<String> filter = (value) -> value.contains("e");

        final UnsupportedOperationException exception =
            assertThrowsExactly(UnsupportedOperationException.class, () -> cache.values().removeIf(filter));
        assertEquals("Cannot remove from ValueCollection", exception.getMessage());
    }