I have just been informed that the support for OOTB monitoring of Spring WS is not in 10.4 nor anywhere on the road map. So Spring WS monitoring will be done via a Field Pack for the foreseeable future.
Currently, I am using a field pack: springMonitoring.andreasreiss.201508301314 that I thought I download from here but now looking at Document directory I cannot seem to find it. The only WebServices FP that I see now is the SOAP WebServices Addon https://communities.ca.com/docs/DOC-108470560
As you may have noticed in my backendpath post I was able to keep using the Field Pack springMonitoring.andreasreiss.201508301314 along with the OOTB support for Spring HTTP by modifying the spring-toggles.pbd and turning off the support for Spring HTTP Rest in the field pack:
# Support for Rest Web Service calls (discovery and correlation)#TurnOn: RestServiceTracing#TurnOn: ClientHttpRequestTracing
Including reian06 Hiko_Davis to get their take on your issue
There is an official supported Spring Monitoring APM extension that supports Spring 3.x and Spring 4.x on APM 9.1+ in new mode. You can open a support ticket to obtain the latest version.