Parameter Validation

Add more flexible parameter validation to Jersey.

In particular, the solution should at least include the ability to check if a
parameter is present and raise an error if is not.
In general and eventually the solution should allow flexible parameter validation.

Possible solutions:

1) Jersey supports an @Required annotation; or

2) Exposes a lower-level abstraction of MultivaluedParameterExtractor
(which is an internally used interface):

public interface MultivaluedParameterExtractor

{ Object extract(MultivaluedMap parameters); }

public interface MultivaluedParameterExtractorProvider { }

public interface MultivaluedParameterExtractorWorkers { }

and the same type of pattern can be utilized.

3) One can utilize AOP method-level interceptors to support @Required
and check for a null value. This solution is much better if one needs to take
into account more than one value.

I also wonder if there is a more general approach to parameter
validation we can apply with the bean validation framework.
#### Environment
Operating System: All
Platform: All
URL: [http://n2.nabble.com/Required-parameters-on-a-Resource-td3446928.html](http://n2.nabble.com/Required-parameters-on-a-Resource-td3446928.html)