title: Spring Data ReST ref link omission when null or empty
body: <p>I've been scouring the docs and the <a href="https://github.com/olivergierke/spring-restbucks" rel="nofollow">Restbucks implementation by Oliver</a> but I don't seem to be able to configure the links on a generated Spring REST repository resource. (I can add to them, but cannot remove them via the ResourceProcessor as the processor is invoked prior to conversion by the looks of things)</p>
  
  <p>My case is quite simple and that is I wish to omit rel links on objects that point to null or an empty collections (such as in the case of say a graph node parent/child structure)</p>
  
  <p>Would anybody have any incite as to how I could achieve this? Ideally I would like to have something suggested in the Restbucks README (but I cannot find it used) where a custom RestResourceEntityLinks extension would be picked up and links generated from said implementation as my case applies to all domain objects.</p>
  
  <p>But perhaps there is an easier way that I am yet to come across? Or perhaps having these links point to an empty array or null is a valid hateoas ref so I should just leave it be and move on?</p>
  
  <p>Thanks in advance</p>