MC-86: Associates attributes to attribute sets and groups

| Q                    | A
| -------------------- | ---
| Bug fix?             | n
| New feature?         | y
| Specs pass?*         | y
| Checkstyle issues?** | n
| PMD issues?***       | n
| Fixed tickets        | MC-86
| Doc PR               |
->join() is an alias of ->innerJoin()