add assertion message

Author: wreulicke

spar-wings-monolith/src/main/java/jp/xet/sparwings/spring/security/DynamoPersistentTokenRepository.java

@@ -83,7 +83,7 @@ public void afterPropertiesSet() {
 
 	@Override
 	public void createNewToken(PersistentRememberMeToken token) {
-		Assert.notNull(token);
+		Assert.notNull(token, "token is requied");
 		if (logger.isTraceEnabled()) {
 			logger.trace("Create token: username={}, series={}, tokenValue={}, date={}", new Object[] {
 				token.getUsername(),