code: public SortedSet<String> getDefinedChanges() {
          SortedSet<String> names = new TreeSet<>();
          for (Change change : findAllInstances()) {
              names.add(getChangeMetaData(change).getName());
          }
          return Collections.unmodifiableSortedSet(names);
      }
docs: Returns all defined changes in the registry. Returned set is not modifiable.