void assertReceivedItemCount(final Config config, final int count) {
        TestUtil.waitForIt(
                () -> {
                    final long actualCount = getForwardFiles(config)
                            .stream()
                            .map(ForwardFileItem::zipItems)
                            .flatMap(Collection::stream)
                            .filter(zipItem -> zipItem.type.equals(StroomZipFileType.META))
                            .count();
                    return actualCount;
                },
                (long) count,
                () -> "Forwarded file pairs count",
                Duration.ofMinutes(2),
                Duration.ofSeconds(1),
                Duration.ofSeconds(5));

        final long actualCount = getForwardFiles(config)
                .stream()
                .map(ForwardFileItem::zipItems)
                .flatMap(Collection::stream)
                .filter(zipItem -> zipItem.type.equals(StroomZipFileType.META))
                .count();
        Assertions.assertThat(actualCount)
                .isEqualTo(count);
    }
Assert all the {@link UniqueId}s contained in the stored aggregates
stroom-proxy/stroom-proxy-app/src/test/java/stroom/proxy/app/MockFileDestination.java