Pega is very judicious with its use of memory on the application server and disk space on the database. Pega does not allocate memory for properties that contain no values. The WorkHistory PageList will appear in the Clipboard once it contains at least one Page with at least one populated Property. You can preemptively place a value in one of the embedded Properties of the first Page of the WorkHistory PageList using the pyDefault Data Transform of the Candidate class. Simply set .WorkHistory(1).CompanyName to the empty string ("") and voila, the .WorkHistory PageList will appear in the Clipboard next time you create a Candidate Case.
Also, if no one minds, I thought maybe I would add a bit of clarfication re when to manually add an action to the pySetFieldDefaults data transform for complex types.
As Henry mentioned, all complex types must be instantiated before they can be used. This is accomplished using the pySetFieldDefaults data transform.
However, if you define a complex type using the Configure form option in the Case Designer (which is what you did in the exercise that starts on page 72 of the exercise guide dated 20141218) Pega 7 will automatically add an action to the pySetFieldDefaults data transform to instantiate that complex type. Notice the entries in Pradeep's screen shot. The .pyLabel property is being set to an empty string for the Candidate, WorkHistory and EducationalBackground complex types.
If you were to create these complex types using the Data Explorer or the App Explorer, you would then need to do just as Henry noted - purposefully add a Set action to the pySetFieldDefaults data transform. You can use pretty much any attribute of the complex type, but Pega uses .pyLabel to keep it consistent.