Hi Astha,
This is quite difficult to debug on this mailing-list without having access to the code unfortunately.
That being said, I suspect the following missing imports from your MANIFEST.MF are the culprit:
javax.xml.bind;resolution:=optional;version="[2.3,3)",javax.xml.bind.annotation;resolution:=optional;version="[2.3,3)",javax.xml.bind.annotation.adapters;resolution:=optional;version="[2.3,3)"
Make sure the plugin jar doesn't contain any of these libraries (javax.xml.bind:jaxb-api, etc.) and import the jakarta equivalents (jakarta.servlet:jakarta.servlet-api, etc.) as provided (they come from Kill Bill).