HeaderHelper { public static String convertToString(Collection<String> collection) { if (collection == null) { return null; } if (collection.isEmpty()) { return ""; } return Joiner.on(',').join(collection); } private  HeaderHelper(); static List<AcceptMediaType> createAcceptMediaTypeList(String header); static List<AcceptLanguage> createAcceptedLanguageList(String header); static List<AcceptToken> createAcceptedCharsetList(String header); static List<AcceptToken> createAcceptedEncodingList(String header); static List<Cookie> parseCookies(String cookiesString); static NewCookie parseNewCookie(String newCookieString); static Date parseDateHeader(String header); static String formatDate(Date date); static long getContentLengthLong(MultivaluedMap<String, String> httpHeaders); @SuppressWarnings({"unchecked"}) static String getHeaderAsString(Object o); static String convertToString(Collection<String> collection); static final Comparator<QualityValue> QUALITY_VALUE_COMPARATOR; }
@UseDataProvider("forConvertsCollectionToString") @Test public void convertsCollectionToString(Collection<String> header, String expectedResult) throws Exception { final String result = HeaderHelper.convertToString(header); assertEquals(expectedResult, result); }