/**
* A variation of {@link #getAccessor(org.springframework.messaging.Message, Class)} with a {@code
* MessageHeaders} instance instead of a {@code Message}.
*
* <p>This is for cases when a full message may not have been created yet.
*
* @return an accessor instance of the specified type, or {@code null} if none
* @since 4.1
*/
@SuppressWarnings("unchecked")
public static <T extends MessageHeaderAccessor> T getAccessor(
MessageHeaders messageHeaders, Class<T> requiredType) {
if (messageHeaders instanceof MutableMessageHeaders) {
MutableMessageHeaders mutableHeaders = (MutableMessageHeaders) messageHeaders;
MessageHeaderAccessor headerAccessor = mutableHeaders.getMessageHeaderAccessor();
if (requiredType.isAssignableFrom(headerAccessor.getClass())) {
return (T) headerAccessor;
}
}
return null;
}
