title: where to put sourceSets in multiple projects gradle
body: <p>I have a multiple projects gradle, in the top gradle is</p>
  
  <pre><code>subprojects {
  
      apply plugin: "java"
  
      sourceSets {
          main {
              scala {
                  srcDirs = ['src/main/scala', 'src/main/java']
              }
              java {
                  srcDirs = []
              }
          }
      }
  
      repositories {
          mavenCentral()
          maven {
              url "http://repo.springsource.org/milestone"
          }
      }
  }
  </code></pre>
  
  <p>But it complains </p>
  
  <pre><code>&gt; Could not find method sourceSets() for arguments [build_vgdvugn6hqrvg7eo53afh1229$_run_closure1_closure2@19962194] on root project 'testCom'.
  </code></pre>
  
  <p>So where should I put sourceSets?</p>