title: What's wrong with Groovy multi-line String?
body: <p>Groovy scripts raises an error:</p>
  
  <pre><code>def a = "test"
    + "test"
    + "test"
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code>No signature of method: java.lang.String.positive() is 
  applicable for argument types: () values: []
  </code></pre>
  
  <p>While this script works fine:</p>
  
  <pre><code>def a = new String(
    "test"
    + "test"
    + "test"
  )
  </code></pre>
  
  <p>Why?</p>