title: Gradle sync issue : None of the consumable configurations have attributes
body: <p>I wan't to use an external library in my project.
  The fact is that it doesn't behave as I want, so I need to edit classes of it.</p>
  
  <p>To do this, I downloaded the library as a zip folder and added it to my project using this technique <a href="https://stackoverflow.com/q/30344053/9054214">How do you edit a dependency/external library in android studio?</a></p>
  
  <p>After the project sync, I get this in gradle console: </p>
  
  <p><a href="https://i.stack.imgur.com/q4ixb.png" rel="noreferrer"><img src="https://i.stack.imgur.com/q4ixb.png" alt="gradle error console"></a>
  And here is the detail of one of those errors : </p>
  
  <blockquote>
    <p>Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve project :libs:Markwon.</p>
    
    <p>Could not resolve project :libs:Markwon.
    Required by:
        project :app
    Unable to find a matching configuration of project :libs:Markwon: None of the consumable configurations have attributes.</p>
  </blockquote>
  
  <p>I tried lot of things, like setting same buildTypes names in app build.gradle and external library build.gradle like said in threads I found about this problem. I tried with another library and result was the same.</p>
  
  <p>I really don't get it guys, if you have an idea about this problem, or another solution to edit my external library, I would appreciate so much.</p>