add test populateValues with traversable
added testcase for nested Traversable values with nested fieldset
fix value of nested fieldset can be a Traversable
added missing newline
removed @package from docblock
Merge pull request #4927 from youngguns-nl/fieldset_traversable

Nested Fieldset value can be a Traversable
Merge branch 'feature/4927' into develop

Close #4927