This is a feature of JBuilder Enterprise.
The Add New Property dialog box displays when you choose the Add button in the Ant Properties dialog box. An Ant project can have properties, which are the mechanism used to pass parameters to targets and tasks without modifying the existing properties in the build file. Add a new property and value for the Ant build file or override an existing property in this dialog box.
Choose a property name to override with a new value or enter a new property name in this field.
Enter a value for the property in the Name field.