The issue was found and fixed with RA.Web.Service.SOAP 4.4.2 in RA Web Service SOAP Solution. The Package is available for download at the Automic-Support-Zone (https://support.automic.com).
Hotfix-Description: Web Service Agent SOAP Job fails if an endpoint is called that does not send a one way message.
A problem is fixed where a SOAP Job fails if an endpoint is called that does not send a reply message (one way message).
In this case, the Job fails with the following error message:
com.sun.xml.internal.messaging.saaj.SOAPExceptionImpl: Unable to internalize message
The parser exception is caused by an empty Content-Type header.