Camunda Connect does not set the content length of the HTTP requests, which leads to requests which contain the header Transfer-Encoding: chunked. Some REST/Soap endpoint do not support chunked requests and expect and request with Content-Length set. The Connect API only provides a single method to set the payload HttpBaseRequest#payload(String payload) which accepts a String as payload. So Connect is aware of the content size and could always set the content-length to prevent chunked requests. Chunked requests should only be used if the payload size is not known during request creation or the payload should not be buffered before sending the request. Both is not true for the current Connect implementation.
Specify content length on creation of InputStreamEntity.