Some things that you should check first:
atlas-clean- Try version
2.3.1ofjaxb-apifor Confluence7.3.3 - Use
confluence-plugins-platform-pomat least as part of yourdependencyManagementsection to ensure you are having the correct dependency versions. - Try adding an explicit import
javax.xml.bind.*;version:=${jaxb.version} - Use AMPS version
8.1.0(specify in pom.xml or use-u 8.1.0flag)
There is an open problem with some Confluence versions but that affects NoClassDefFoundError - which does not seem to be your problem. NoClassDefFoundError for Spring JDBC classes since Confluence 7.1.1