title: Using existing objects as input in a mutation
body: <p>I am building a graphql API using HotChocolate on ASP.NET.</p>
  <p>I have two types, <code>role</code> as well as <code>permission</code>. <code>permission</code> consists of an id, a name and a description. <code>role</code> is almost the same, but it contains a list of <code>permission</code>'s.
  I have already figured out how to create a <code>permission</code> together with a <code>role</code>.
  Now I need to create a <code>role</code> without creating another <code>permission</code>, instead using an already existing <code>permission</code> in the list of <code>permission</code>'s attribute of the new <code>role</code>. I can't seem to figure out how to do it.</p>
  <p>Surely there must be a way to do that without creating a whole new mutation for this, right?</p>