Requests to MultiSearch endpoint have the wrong "Content-Type" header value

[sivo]

What happened:
Requests to the _msearch endpoint between the web UI and the Grafana server/proxy have a "Content-Type" header set to "application/json", although it is newline-delimited JSON.

This normally would work just fine, except in some configurations where there is a reverse proxy in between (nginx in my case) that for some reason doesn't handle this correctly.

What you expected to happen:
Requests to the _msearch endpoint should have the "Content-Type" header set to "application/x-ndjson". The Elasticsearch datasource does this correctly.

How to reproduce it (as minimally and precisely as possible):
Create a dashboard with a data request using this datasource. Observe headers of the request that is made from the browser when viewing the dashboard.

Environment:

• Grafana version: 9.4.7
• Plugin version: 2.2.0

[kevinwcyu]

Thanks @sivo, I'll put this into our backlog.

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Reference PR to whoever picks this up: grafana/grafana#32282