Because so many methods in PBCS require parameters that are maps and lists, it is very important to your productivity and effectiveness to understand, use, and be able to manipulate collections. Collections include lists, maps, and ranges. These are based on Java collection types and include a ton of useful methods. This article will cover lists and maps.
One of the more surprisingly useful things that can be done in a Groovy calculation is querying metadata. This was discussed in Part 11: Accessing Metadata Properties, but I recently had a situation where users could load data at parent levels and have it allocated down to the bottom of the hierarchies.