anchor.diff:  
   val sql = new SQLContext(sc)
   
  -val people = sql.esDF("spark/people") <3>
  +val people = sql.esDF("spark/people")         <3>
   
   // check the associated schema
   println(people.schema.treeString)             <4>
  
positive.code: ...
  
  DataFrame people = ...
  JavaEsSpark SQL.saveToEs("spark/people");                     <3>
  ----
  
  <1> Spark SQL Java imports
  
negative.code: 
  val sql = new SQLContext(sc)
  
  val people = sql.esRDD("spark/people")        <3>
  
  // check the associated schema
  println(people.schema)                        <4>
  