### Question:
StringUtils { public static String clean(String string) { if (string == null) { return null; } return string.trim(); } StringUtils(); static boolean isEmpty(String string); static String clean(String string); static boolean isAlpha(Character c); static String getBeanName(String queueName); static String convertToCamelCase(String string); static String groupName(String name);  }### Answer:
@Test public void clean() { assertEquals("", StringUtils.clean(" ")); assertEquals("test", StringUtils.clean("test")); assertEquals("test", StringUtils.clean(" test ")); assertEquals("test queue", StringUtils.clean(" test queue ")); }