### Question:
Constants { public static List<String> parseTokens(String tokens) { if (tokens == null || tokens.trim().isEmpty()) { return Collections.emptyList(); } else { return Collections.unmodifiableList(Arrays.asList(tokens.trim().split("\\s+"))); } } private  Constants(); static List<String> parseTokens(String tokens); static String constructTokensString(List<String> tokens); static Map<String, String> parseRFC2617(String header); static String constructRFC2617(Map<String, String> params); static List<String> filterHeaders(List<String> headers); static final String SCHEME; static final String CHALLENGE; static final String REALM; static final String KEY_ID; @Deprecated
    static final String HEADER_REQUEST_LINE; static final String HEADER_REQUEST_TARGET; static final String HEADER_DATE; static final List<String> DEFAULT_HEADERS; static final List<String> IGNORE_HEADERS; static final String AUTHORIZATION; static final String HEADERS; static final String SIGNATURE; static final String ALGORITHMS; static final String ALGORITHM; static final Charset CHARSET; static final Pattern RFC2617_PARAM; static final KeyId DEFAULT_KEY_IDENTIFIER; static final Collection<Algorithm> ALL_SUPPORTED_ALGORITHMS; static final Challenge PREEMPTIVE_CHALLENGE; }### Answer:
@Test public void testParseTokens() { List<String> tokens = Arrays.asList("date", "content-type"); List<String> parsedExpected = Constants.parseTokens("date content-type"); assertEquals("expected format should parse correctly", tokens, parsedExpected); List<String> parsedLegacy = Constants.parseTokens("date content-type "); assertEquals("legacy format should parse correctly", tokens, parsedLegacy); }