The DummyPlugin step is a reference step plugin that adds a single value to the incoming rows. This page concerns the variation that will run on version 3 of Pentaho Data Integration.
The source code can be obtained through Subversion over here.
Download the attachment DummyPlugin3.zip and unzip it in the plugins/steps/ directory of your Pentaho Data Integration distribution. Version 3 or higher is required for this plugin to work.