title: gradle run task on external project
body: <p>Let's say I have two independent projects:</p>
  
  <pre><code>./
    |
    +- projectA
    |  |
    |  + build.gradle
    |  + settings.gradle
    |  + gradlew
    |  + .gradle/
    |  + gradle/
    |  + submodulea/
    |
    +- projectB
       |
       + build.gradle
       + settings.gradle
       + gradlew
       + .gradle/
       + gradle/
       + submoduleb/
  </code></pre>
  
  <p>I'd lile to execute certain tasks for <code>:projectB:submoduleb</code> from the buildscript of <code>:submoduleA</code>. For example:</p>
  
  <p><strong>projectB/submoduleb/build.gradle</strong>:</p>
  
  <pre><code>//...
  task test() {
      println 'hello from :projectB:submoduleb'
  }
  //...
  </code></pre>
  
  <p>How do I call <code>test</code> from <strong>projectA/build.gradle</strong> ?</p>