Content-Length is missing

Hi. Several days ago our script received a strange error while we are trying to add a new contact by this URL https://api.infusionsoft.com/crm/rest/v1/campaigns/681/sequences/4/contacts/480557
Errors told us, that wasn’t set Content-length header, but it does. What’s happened?

 [request] => POST https://api.infusionsoft.com/crm/rest/v1/campaigns/681/sequences/4/contacts/480557
[request_made_at] => 2020-02-28 08:17:36
[request_headers] => Array
    (
        [Authorization] => Bearer KKKEy
    )

[request_data] => Array
    (
    )

[response_code] => 411
[response_headers] => Array
    (
        [Date] => Fri, 28 Feb 2020 08:17:36 GMT
        [Content-Type] => application/json
        [Content-Length] => 122
        [Connection] => keep-alive
        [X-Frame-Options] => DENY
        [Strict-Transport-Security] => max-age=86400
        [X-Content-Type-Options] => nosniff
        [Content-Security-Policy] => frame-ancestors 'none'
        [X-XSS-Protection] => 1
    )

[response_data] => Array
    (
        [fault] => Array
            (
                [faultstring] => Content-Length is missing
                [detail] => Array
                    (
                        [errorcode] => messaging.adaptors.http.flow.LengthRequired
                    )

            )

    )

That error is saying you are not setting a Content-Length header in the request. The logging you provided is showing the Content-Length header is the response we sent you. Usually the HttpClient sets that header for you automatically.