title: Classes of imported library are "locked", what can I do to import them?
body: <p>I have created a personal library with two classes I'd like to use: Mylib -&gt; YoavJava -&gt; Trie + Node.
  I imported the library by going to File -&gt; Project Structure -&gt; Modules -&gt; &quot;+&quot; -&gt; added the library.
  It is showing the library under &quot;External Libraries&quot;, but it seems as if the classes are &quot;locked&quot;, it even has a small lock on the bottom right hand side of the class icon. I am not able to use the library in my project (e.g., I have tried to instantiate a new instance of the Trie class. It is marked red and it would not suggest to import the class).
  I am including a screenshot describing my problem:
  <a href="https://i.stack.imgur.com/Dy4L0.png" rel="nofollow noreferrer">Screenshot</a></p>