How do I access username and password in a Camel processor when using Spring Security with Camel on EAP?

Issue

• I used a reference example camel-example-spring-security listed in: http://camel.apache.org/spring-security-example.html
• Now I am wondering how I pass username and password in my client code so that my Camel processor can access it:
• In code below, however, username, password are coming as null:

String username = exchange.getIn().getHeader("username", String.class);
String password = exchange.getIn().getHeader("password", String.class);

Authentication authToken = new UsernamePasswordAuthenticationToken(username, password);
SecurityContextHolder.getContext().setAuthentication(authToken);

• When I call setAuthentication() method everything seems to be working except I just need a way to collect username and password from Exchanges's header.
• If I do not call setAuthentication(), I get an error org.apache.camel.Camel.AuthorizationException: Cannot find the Authentication instance. I believe the cause is, it cannot find Exchange.AUTHENTICATION in the message header.
• How can I access username and password from the message header?