### Question:
ProxyUtils { public static Class<?>[] getAllInterfaces(Class<?> cls) { return cls == null ? null : ClassUtils.getAllInterfaces(cls).toArray(ArrayUtils.EMPTY_CLASS_ARRAY); } private  ProxyUtils(); static Class<?>[] getAllInterfaces(Class<?> cls); static String getJavaClassName(Class<?> clazz); static Class<?> getWrapperClass(Class<?> primitiveType); static T nullValue(Class<T> type); static boolean isEqualsMethod(Method method); static boolean isHashCode(Method method); static ProxyFactory proxyFactory(); static final Object[] EMPTY_ARGUMENTS; static final Class<?>[] EMPTY_ARGUMENT_TYPES; }### Answer:
@Test public void testGetAllInterfaces() { assertNull(ProxyUtils.getAllInterfaces(null)); assertEquals(Arrays.asList(new Class[] { DuplicateEcho.class, Serializable.class, Echo.class }), Arrays.asList(ProxyUtils.getAllInterfaces(EchoImpl.class))); }