Creating the onPlacement Method

Regardless of whether you are using the Spark data frame template, you must override the onPlacement() method.

Before you beginCreate the GUI node class.
This describes the parameters of the OperatorDialog in the GUI. The other two methods, onInputorParameterChange and onOutputVisualization, are implemented in a future tutorial. They are not needed for this basic example.
    Procedure
  1. Add the following code: 
    override def onPlacement(operatorDialog: OperatorDialog,
    operatorDataSourceManager: OperatorDataSourceManager,
    operatorSchemaManager: OperatorSchemaManager): Unit = {
   // code for operatorDialog goes here
}
What to do nextBuild the Operator dialog.