java.lang.ClassCastException: org.restlet.data.Parameter cannot be cast to org.r

Restlet header传参异常：java.lang.ClassCastException: org.restlet.data.Parameter cannot be cast to org.restlet.engine.header

原因：
The object returned by Response/Request.getAttributes().get("org.restlet.http.headers") is a Series

, not a Form, which is a Series. Because of type erasure, there is no runtime problem until the Restlet Engine tries to make use of the Parameter you stored and treat it as a Header.

private static final String HEADERS_KEY = "org.restlet.http.headers";

...

@SuppressWarnings("unchecked")

static Series

getMessageHeaders(Message message) {

ConcurrentMap attrs = message.getAttributes();

Series

headers = (Series

) attrs.get(HEADERS_KEY);

if (headers == null) {
headers = new Series

(Header.class);
Series

prev = (Series

)
attrs.putIfAbsent(HEADERS_KEY, headers);
if (prev != null) { headers = prev; }
}

return headers;

}

...

// In some method, what you originally wanted to do:
getMessageHeaders(getResponse()).add("Access-Control-Allow-Origin", "*");
//or getRequest()