protected String toString(final Map<String, String> configuration) {
        return String.join(", ", configuration.entrySet().stream().map(entry -> String.format("%s%s",
            entry.getKey(), StringUtils.isNotBlank(entry.getValue()) ? String.format("=%s", entry.getValue()) : StringUtils.EMPTY)).collect(Collectors.toList()));
    }
@Test
    public void testToString() {
        final Map<String, String> properties = new LinkedHashMap<>();
        properties.put("fs.sync.mode", "online");
        properties.put("fs.sync.indexer.enable", "");
        properties.put("fs.lock.enable", "");
        properties.put("fs.buffer.enable", "");
        assertEquals("fs.sync.mode=online, fs.sync.indexer.enable, fs.lock.enable, fs.buffer.enable",
            new BrickPreferencesRequestInterceptor().toString(properties));
    }