### Question:
AdminCacheUtils { public final boolean validateKey(final String key) { return keyPattern.matcher(key).matches(); } private  AdminCacheUtils(); DataProvider getProvider(final Class clazz); final boolean validateKey(final String key); static AdminCache getCache(); static AdminCacheUtils getInstance();  }### Answer:
@Test public void testValidateKey() { assertTrue(acu.validateKey("kurt")); assertTrue(acu.validateKey("kurt.cobain")); assertTrue(acu.validateKey("kurt-cobain")); assertTrue(acu.validateKey("kurt_cobain")); assertFalse(acu.validateKey("kurt.cobain@nirvana")); assertFalse(acu.validateKey("kurt.cobain#nirvana")); assertTrue(acu.validateKey("kurt.cobain/smells.like.teen.spirit")); assertFalse(acu.validateKey("/kurt.cobain/smells.like.teen.spirit")); assertTrue(acu.validateKey("kurt.cobain/smells.like.teen.spirit/")); }