listObjects only returns the first match

[ggallani-chwy]

I have the following folder structure for my file-based S3Mock:

Searching my bucket with the "2020/12/30/" prefix returns one common prefix instead of 2.

api = new S3Mock.Builder()
            .withFileBackend("src/test/resources/s3")
            .withPort(8001)
            .build();
        api.start();

...

@Test
    public void test_s3_setup() {
        SdkHttpClient httpClient = UrlConnectionHttpClient.builder()
            .connectionTimeout(Duration.ofSeconds(10))
            .socketTimeout(Duration.ofSeconds(10))
            .build();
        S3Configuration config = S3Configuration.builder()
            .pathStyleAccessEnabled(true)
            .build();
        S3Client client = S3Client.builder()
            .endpointOverride(URI.create("http://localhost:8001"))
            .credentialsProvider(AnonymousCredentialsProvider.create())
            .httpClient(httpClient)
            .serviceConfiguration(config)
            .build();

        ListObjectsRequest listObjectsRequest = ListObjectsRequest
            .builder()
            .bucket(BUCKET_NAME)
            .prefix("2020/12/30/")
            .delimiter("/")
            .build();
        ListObjectsRequest listObjectsRequestB = ListObjectsRequest
            .builder()
            .bucket(BUCKET_NAME)
            .prefix("2020/12/30/BASELINE/")
            .delimiter("/")
            .build();
        ListObjectsRequest listObjectsRequestT = ListObjectsRequest
            .builder()
            .bucket(BUCKET_NAME)
            .prefix("2020/12/30/TEST/")
            .delimiter("/")
            .build();

        List<String> buckets = client.listBuckets().buckets().stream().map(Bucket::name).collect(Collectors.toList());
        assertTrue(buckets.contains(BUCKET_NAME)); // works

        List<String> baseline = client.listObjects(listObjectsRequestB).commonPrefixes().stream()
            .map(CommonPrefix::prefix).collect(Collectors.toList());
        assertThat(baseline)
            .isEqualTo(List.of("2020/12/30/BASELINE/BATCH_PRICING_INFO/")); // works

        List<String> test = client.listObjects(listObjectsRequestT).commonPrefixes().stream()
            .map(CommonPrefix::prefix).collect(Collectors.toList());
        assertThat(test)
            .isEqualTo(List.of("2020/12/30/TEST/BATCH_PRICING_INFO/")); // works

        List<String> envs = client.listObjects(listObjectsRequest).commonPrefixes().stream()
            .map(CommonPrefix::prefix).collect(Collectors.toList());
        assertThat(envs)
            .isEqualTo(List.of("2020/12/30/BASELINE/", "2020/12/30/TEST/")); // fails, the response only contains "2020/12/30/BASELINE/"
    }