Let's say you'd love to use Enunciate's documentation features and you've got a REST API, but you're not using JAX-RS. You've got a couple of options.
Option 1: Create some interfaces without an implementation
One thing you could do is just create some interfaces that define your API in terms of JAX-RS, but don't supply an associated implementation class. Enunciate will pick up on your interfaces and generate the associated documentation.
Option 2: Apply "hints" to your existing code
The problem with option 1 is that you have to maintain the metadata in a separate place from where you maintain your API. There is a higher probability that the documentation will be out-of-sync.
The second option is that you can supply Enunciate with the necessary JAX-RS metadata using the
@org.codehaus.enunciate.contract.jaxrs.ResourceMethodSignature annotation. Here's an example of how you might use this annotation: