Body seems not being proparly processed?

[Danny de Waard]

I have a blackbox entry like:

  http_post_2xx_basics:

    prober: http

    timeout: 5s

    http:

      headers:

        User-Agent: "blackbox-monitoring"

        Content-Type: "application/json"

        Accept: "application/json"

        Private-ApiKey: "myAPIKey"

        Body: '{"some_arrangements": [{"arrangement_number": "0004074331","administration_code": "1006"}]}'

      valid_status_codes:

      - 200

      method: POST

And i call the entry via prometheus scrape:

  - job_name: blackbox_api_basics

    scrape_interval: 60s

    metrics_path: /probe

    params:

      module: [http_post_2xx_basics]

    static_configs:

      - targets: ['https://my.domain.com/appl/api/products/details/basics']

        labels:

          name: 'Basic details'

    relabel_configs:

     - source_labels: [__address__]

       target_label: __param_target

     - source_labels: [__param_target]

       target_label: instance

     - target_label: __address__

       replacement: 127.0.0.1:9115 # The blackbox exporter.

But i always get a http 400 back.
In postman the same call returns a neat 200 ?
Is there something that needs quoting/unquoting or something?