title: Class that describes a immutable, ordered set
body: <p>I need some class/interface name that describes an immutable, ordered set (in input order, like <code>LinkedHashSet</code>). I can of course just use the class like this:</p>
  
  <pre><code>class Foo {
      public final Set&lt;Long&gt; frozenOrderedSet;
  
      public Foo(List&lt;Long&gt; input) {
          frozenOrderedSet = Collections.unmodifiableSet(new LinkedHashSet(input));
      }
  }
  </code></pre>
  
  <p>But this would not clarify my approach. I would like to make it clear to everyone reading the source that the Set is unmodifiable and unique while maintaining it's order with <code>for(Long l : set){}</code>.</p>