See JSR 109, version 1.3 final spec, section 5.3.2.1 javax.jws.WebService annotation

Following default mapping rules apply for Web modules that contain Servlet based endpoints that use this
annotation but do not package a web.xml or a partial web.xml:
• fully qualified name of the Service Implementation Bean class maps to <servlet-name> element in
web.xml.
• fully qualified name of the Service Implementation Bean class maps to <servlet-class> element in
web.xml (also specified in section 7.1.2)
• serviceName attribute of javax.jws.WebService annotation prefixed with "/" maps to <url-pattern>
element in web.xml. If the serviceName attribute in javax.jws.WebService annotation is not
specified, then the default value as specified in JSR-181 specification is used.