title: Gradle Error configurations.add String cannot be cast to Configuration
body: <p>My gradle file says</p>
  
  <pre><code>configurations.add "externalDeps"
  </code></pre>
  
  <p>If I run gradle with 1.4 I don't have a problem.</p>
  
  <p>If I run gradle with 2.0 I get the following error:</p>
  
  <pre><code>Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to org.gradle.api.artifacts.Configuration
      at org.gradle.api.artifacts.Configuration$Namer.determineName(Configuration.java:87)
      at org.gradle.api.internal.DefaultNamedDomainObjectCollection.add(DefaultNamedDomainObjectCollection.java:70)
      at org.gradle.api.NamedDomainObjectCollection$add$0.call(Unknown Source)
      at build_3p9qdtholqj79o8rnevdt3d7t0.run(D:\Code\trunk\projects\build.gradle:6)
      at org.gradle.groovy.scripts.internal.DefaultScriptRunnerFactory$ScriptRunnerImpl.run(DefaultScriptRunnerFactory.java:52)
      ... 82 more
  </code></pre>
  
  <p>What has changed that is causing this error?</p>
  
  <p>How should I be defining this now?</p>