How can I validate a OAuth signature received in a request using Signpost Java library

Question

I'm using SignPost successfully in a project to sign outgoing requests (with HttpClient). Now I need to validate/verify the signature in the requests I receive. I have no idea how to do it and I can't find any code example.

Can anybody point me to any example on how to achieve this? (I have the consumer key and consumer secret, of course, which I don't know if I must use in the verification process)

Thanks, Ignacio