Steps to reproduce

1. Create a content type view with mandatory sub-elements (in composite or fieldset)
2. Copy a content of this type
3. Paste the content as a new content (copy based on the view defined above, can be the main view, checkByDefault should be set to false).
4. Go to advanced mode.
5. Parent elements of mandatory fields are not checked.
6. Don't touch at the configuration and click on OK.
7. All attributes are copied instead of only mandatory ones.
   

Non-regression tests

• Behaviour on checking/unchecking children and parents
• Simply mode: should copy all attributes
• checkByDefault to false and true behaviour (at loading and during the copy)

Linked to issue CMS-10958