[FrameworkBundle] Fixed bug in XMLDescriptor

| Q                    | A
| -------------         | ---
| Bug fix?          | yes
| New feature?   | no
| BC breaks?     | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets  | 
| License          | MIT
| Doc PR           | 

Fixed bug in container:debug command where parameter value doesn't get printed.