title: How to use sync and Unless together in Cacheable? Any workaround?
body: <p>I have a use case where I need to use sync and I don't want to cache if the method returns null. How can I do it?</p>
  <pre><code>@Cacheable(value = &quot;abc&quot;, sync = true, unless = &quot;#result!=null&quot;)
  </code></pre>
  <p>currently this is not supported in Spring.
  I am using Spring 5.2.2</p>