How to Set Default Value of User input, Make it Required or Read Only

A code sample worth a thousand words:

def qty = api.integerUserEntry("Quantity")	// set up the user input as usual

def p = api.getParameter("Quantity")		// retrieve the context parameter with the same name as the input
if (p != null && p.getValue() == null) {
  p.setLabel("Quantity (default: 1)") 		// set the displayed label
  p.setRequired(true) 						// set the mandatory hint
  p.setReadOnly(false) 						// set the read only flag
  p.setValue(1) 							// set the default value with which the input is pre-populated
}
return qty ?: 1 							// if user doesn't specify a value, return 1

The same approach works for combo boxes:

def competitorNames = [ "SODEXO", "COMPASS" ]

def competitor = api.option("Competitor", competitorNames)
def p = api.getParameter("Competitor")
if (p != null && p.getValue() == null) {
  p.setLabel("Primary Competitor")
  p.setValue(competitorNames[0])
}
return competitor

There are many more properties you can change. For the complete list of available methods see the latest documentation on the ContextParameter class.