protected String getAuthzHeader(ServletRequest request) {
        HttpServletRequest httpRequest = WebUtils.toHttp(request);
        return httpRequest.getHeader(AUTHORIZATION_HEADER);
    }
Returns the {@link #AUTHORIZATION_HEADER AUTHORIZATION_HEADER} from the specified ServletRequest.
<p/>
This implementation merely casts the request to an <code>HttpServletRequest</code> and returns the header:
<p/>
<code>HttpServletRequest httpRequest = {@link WebUtils#toHttp(ServletRequest) toHttp(request)};<br/>
return httpRequest.getHeader({@link #AUTHORIZATION_HEADER AUTHORIZATION_HEADER});</code>

@param request the incoming <code>ServletRequest</code>
@return the <code>Authorization</code> header's value.
web/src/main/java/org/apache/shiro/web/filter/authc/HttpAuthenticationFilter.java