### Question:
GravatarUtil { public static String generateHash(String emailAddress) { if (StringUtils.isBlank(emailAddress)) { return null; } return DigestUtils.md5Hex(emailAddress.trim().toLowerCase()).toLowerCase(); } private  GravatarUtil(); static String generateHash(String emailAddress); static String getGravatarUrl(UserPrincipal userPrincipal); static String getGravatarUrl(UserPrincipal userPrincipal, int size); static String getGravatarUrl(String emailAddress); static String getGravatarUrl(String emailAddress, int size);  }### Answer:
@Test public void generateHashTest() { Assert.assertEquals("e64c7d89f26bd1972efa854d13d7dd61", GravatarUtil.generateHash("admin@example.com")); }