Provider com.sun.xml.ws.spi.ProviderImpl not found

We have developed a Jira plugin which integrate SAP system via SOAP web service. The plugin has compile scope dependency in pom as shown below:

com.sun.xml.ws
jaxws-rt
4.0.0

The SOAP call works fine when it is triggered via servlet (REST endpoint). However, when it is triggered from a Jira event-listener call back, the instantiation of Stub SOAP service fails with exception Provider com.sun.xml.ws.spi.ProviderImpl not found. As far as I know the SOAP support has been removed from Jira 7.0.0, but the plugin has it own dependencies to the jws-rt lib. Anyone has an idea why it fails in Jira event call back while it works with servlet? Our Jira Server version is 9.4.10.