[fluentd over http ]encoding "application/x-ndjson" is an invalid parameter

3. Forward logs to fluentd receiver over http:
{
    "apiVersion": "logging.openshift.io/v1",
    "kind": "ClusterLogForwarder",
    "metadata": {
        "name": "instance",
        "namespace": "openshift-logging"
    },
    "spec": {
        "outputs": [
            {
                "http": {
                    "headers": {
                        "h1": "v1",
                        "h2": "v2"
                    },
                    "method": "POST"
                },
                "name": "httpout-app",
                "type": "http",
                "url": "http://fluentdserver-fluentdserver.apps.anli13.qe.devcluster.openshift.com/logs/app"
            },
            {
                "http": {
                    "headers": {
                        "h1": "v1",
                        "h2": "v2"
                    },
                    "method": "POST"
                },
                "name": "httpout-infra",
                "type": "http",
                "url": "http://fluentdserver-fluentdserver.apps.anli13.qe.devcluster.openshift.com/logs/infra"
            },
            {
                "http": {
                    "headers": {
                        "h1": "v1",
                        "h2": "v2"
                    },
                    "method": "POST"
                },
                "name": "httpout-audit",
                "type": "http",
                "url": "http://fluentdserver-fluentdserver.apps.anli13.qe.devcluster.openshift.com/logs/audit"
            }
        ],
        "pipelines": [
            {
                "inputRefs": [
                    "application"
                ],
                "name": "app-logs",
                "outputRefs": [
                    "httpout-app"
                ]
            },
            {
                "inputRefs": [
                    "infrastructure"
                ],
                "name": "infra-logs",
                "outputRefs": [
                    "httpout-infra"
                ]
            },
            {
                "inputRefs": [
                    "audit"
                ],
                "name": "audit-logs",
                "outputRefs": [
                    "httpout-audit"
                ]
            }
        ]
    }
}

<label @HTTPOUT_AUDIT>
  <match **>
    @type http
    endpoint http://fluentdserver-fluentdserver.apps.anli13.qe.devcluster.openshift.com/logs/audit
    http_method post
    encoding "application/x-ndjson"
    headers {"h1":"v1","h2":"v2"}

    <buffer>
      @type file
      path '/var/lib/fluentd/httpout_audit'
      flush_mode interval
      flush_interval 1s
      flush_thread_count 2
      retry_type exponential_backoff
      retry_wait 1s
      retry_max_interval 60s
      retry_timeout 60m
      queued_chunks_limit_size "#{ENV['BUFFER_QUEUE_LIMIT'] || '32'}"
      total_limit_size "#{ENV['TOTAL_LIMIT_SIZE_PER_BUFFER'] || '8589934592'}"
      chunk_limit_size "#{ENV['BUFFER_SIZE_LIMIT'] || '8m'}"
      overflow_action block
      disable_chunk_backup true
    </buffer>
  </match>