title: How do I set a box link to never expire via the content API?
body: <p>I need to set a box link to never expire.  </p>
  
  <p>The API guide doesn't describe how to do this:
  <a href="https://box-content.readme.io/reference#create-a-shared-link-for-a-folder" rel="nofollow">https://box-content.readme.io/reference#create-a-shared-link-for-a-folder</a> </p>
  
  <p>I've opened a request on the box communities page, but I'm hoping someone here might know and save me the wait!</p>
  
  <p>I have tried sending both 'NULL' and blank string '' in the field "unshared_at".  </p>
  
  <p>NULL just defaulted to the standard date. Blank string failed entirely.</p>