title: Spark/Scala - Rename the Columns Produced by List
body: <p>How to rename the <code>_1</code>, <code>_2</code> to meaningful column names in Spark/Scala?</p>
  
  <pre><code>root
     |-- aaa: string (nullable = true)
     |-- bbb: array (nullable = true)
     |    |-- element: struct (containsNull = true)
     |    |    |-- _1: string (nullable = true)
     |    |    |-- _2: long (nullable = false)
  </code></pre>