@Override
    public Map<K, V> loadAll(Collection<K> keys) {
        long startNanos = Timer.nanos();
        try {
            return delegate.loadAll(keys);
        } finally {
            loadAllProbe.recordValue(Timer.nanosElapsed(startNanos));
        }
    }
@Test
    public void loadAll() {
        Collection<String> keys = asList("key1", "key2");
        Map<String, String> values = new HashMap<>();
        values.put("key1", "value1");
        values.put("key2", "value2");

        when(delegate.loadAll(keys)).thenReturn(values);

        Map<String, String> result = cacheLoader.loadAll(keys);

        assertSame(values, result);
        assertProbeCalledOnce("loadAll");
    }