@Path("ext/{dataSource}")
    public Object getExtensionResource(
            @PathParam("dataSource") String authProviderIdentifier)
            throws GuacamoleException {

        // Pull UserContext defined by the given auth provider identifier
        UserContext userContext = session.getUserContext(authProviderIdentifier);

        // Pull resource from user context
        Object resource = userContext.getResource();
        if (resource != null)
            return resource;

        // UserContext-specific resource could not be found
        throw new GuacamoleResourceNotFoundException("No such resource.");

    }
Returns the arbitrary REST resource exposed by the UserContext
associated with the AuthenticationProvider having the given identifier.

@param authProviderIdentifier
    The unique identifier of the AuthenticationProvider associated with
    the UserContext whose arbitrary REST service is being retrieved.

@return
    The arbitrary REST resource exposed by the UserContext exposed by
    this UserContextresource.

@throws GuacamoleException
    If no such resource could be found, or if an error occurs while
    retrieving that resource.
guacamole/src/main/java/org/apache/guacamole/rest/session/SessionResource.java