Ad Targeting - Find Entities by URNs API ClassCast

I have some problem with the "Find Entities by URNs" API in order to retrieve the metadata and value information for a collection of URNs.

If I use the URL described in the doc (Sample request) with a valid access token:

https://api.linkedin.com/v2/adTargetingEntities?q=urns&urns=List(urn%3Ali%3AfieldOfStudy%3A100990,urn%3Ali%3Aorganization%3A1035,urn%3Ali%3Aseniority%3A9)&locale=(language:en,country:US)&oauth2_access_token=<a-valid-token>

I receive the message:

{
    "serviceErrorCode": 0,
    "message": "java.lang.ClassCastException",
    "status": 500
}

Anyone have experience the same issue? Any idea how to fix it?

Also: how can i contact for technical support as in this case?

UPDATE:

I made some try and I fix using the following version:

https://api.linkedin.com/v2/adTargetingEntities?q=urns&urns=urn%3Ali%3AfieldOfStudy%3A100990&urns=urn%3Ali%3Aorganization%3A1035&urns=urn%3Ali%3Aseniority%3A9&locale.language=it&locale.country=IT&oauth2_access_token=<a-valid-token>

BUT the locale/language translation is not working. Could be this a working solutions?

From the support team:

Our docs are missing 1 critical piece of information. Whenever using LIST and encoded URNs in the URL, we expect an additional header 'x-restli-protocol-version: 2.0.0'

The correct API call would be Request:

curl -X GET \
'https://api.linkedin.com/v2/adTargetingEntities?q=urns&urns=List(urn%3Ali%3Aindustry%3A1,urn%3Ali%3Aseniority%3A9)&locale=(language:it,country:IT)'
\
-H 'x-restli-protocol-version: 2.0.0' \
-H 'Authorization: Bearer <Token>'

Response:

{
    "elements": [
        {
            "facetUrn": "urn:li:adTargetingFacet:industries",
            "name": "Difesa e spazio",
            "urn": "urn:li:industry:1"
        },
        {
            "facetUrn": "urn:li:adTargetingFacet:seniorities",
            "name": "Partner",
            "urn": "urn:li:seniority:9"
        }
    ],
    "paging": {
        "count": 2147483647,
        "links": [],
        "start": 0
    }
}

Yes, it does provide a response in locale.

Hope this can help other guys in the future