title: Play framework - java.lang.RuntimeException: No main class detected
body: <p>I am new to play framework and trying to run securesocial as in <a href="https://github.com/jaliss/securesocial">https://github.com/jaliss/securesocial</a>
  Using Play 2.3, Scala 2.10.0</p>
  
  <p>.sbt file is configured as</p>
  
  <pre><code>name := "SecureSocial-parent"
  
  version := Common.version
  
  scalaVersion := Common.scalaVersion
  
  lazy val core =  project.in( file("module-code") ).enablePlugins(PlayScala)
  
  lazy val scalaDemo = project.in( file("samples/scala/demo") ).enablePlugins(PlayScala).dependsOn(core)
  
  lazy val javaDemo = project.in( file("samples/java/demo") ).enablePlugins(PlayJava).dependsOn(core)
  
  lazy val root = project.in( file(".") ).aggregate(core, scalaDemo, javaDemo) .settings(
       aggregate in update := false
     )
  </code></pre>
  
  <p>But getting below error</p>
  
  <pre><code>~\securesocial-master&gt;activator run
  [info] Loading project definition from ~\securesocial-master\project
  [info] Set current project to SecureSocial-parent (in build file:~/securesocial-master/)
  java.lang.RuntimeException: No main class detected.
          at scala.sys.package$.error(package.scala:27)
  [trace] Stack trace suppressed: run last securesocial-master/compile:run for the full output.
  [error] (securesocial-master/compile:run) No main class detected.
  </code></pre>
  
  <p>The project compiled successfully with many warnings on deprecated API
  Any pointer will be useful on how to resolve the no main class error</p>