org.springframework.expression-3.1.0.M2.jar has no source attachment

问题

I am working on spring mvc 3.0 that integrated spring-social-facebook. When I debug the code, there is an error at line

List<Connection<?>> connections = connectionRepository.findConnections(providerId);

in the following method

@RequestMapping(value="/{providerId}", method=RequestMethod.GET)
public String connectionStatus(@PathVariable String providerId, 
                               NativeWebRequest request, 
                               Model model) {...} 

and controller is ConnectController

Eclipse shows

Source not found

And when i keep the line inside try catch block, then error message is

Expression parsing failed; nested exception is org.springframework.expression.spel.SpelEvaluationException: EL1007E:(pos 22): Field or property 'name' cannot be found on null

I have added the org.springframework.expression-3.1.0.M2.jar file in WEB-INF/lib. I have also tried this using "Add External Jars..". Any help would be appreciated.

来源：https://stackoverflow.com/questions/7877352/org-springframework-expression-3-1-0-m2-jar-has-no-source-attachment