The content for the secondary languages is not returned when using a multivalue composite field. When specifying a language with the "lang" parameter in the rest call, the content for the language specified is not retrieved unless the language matches the fallbackLocale.

Steps To Reproduce

• Make sure you have i18n enabled on your site
• Create a simple delivery endpoint to retrieve nodes from pages
• Create a dialog containing a multivalue composite field with i18n
• Create some values for this new field for both languages
• Use rest to retrieve the nodes for this newly created content. Make sure to use language parameters in your query ie.e lang=de , lang=en, lang=all etc. 

Actual Result
You will only receive results for the content using the fallbackLocale that is currently in place. Or if using lang=all. lang=de will not return its respective content.

Expected Result
You will receive results for any language you’ve specified within your query.

Additional Notes
This was tested on 6.2.3 using the config for Magnolia 6 UI

Workaround
use lang=all to retrieve all nodes and parse the response to retrieve the language required. (Not ideal or efficient)