This is a normal process since Servlet-API 2.5 which is looking for Servlet related Annotations in all Classes and Jars. Normally this could be avoided with the "metadata-complete" option in the web.xml:
<web-app metadata-complete="true" ...>
In Jetty 8.1.2 this is recognized due startup by the AnntionConfiguration Class but the scanning process occurs anyway. This is an known ISSUE Jetty 8.1.2 scans all classes on classpath if there is >= 1xServletContainerInitializer with HandlesTypes on the classpath, regardless of metadata-complete="true" for Jetty 8.1.2.
A workaround is to use a pattern to limit the JAR files which will be included in the scanning process. E.g. in Eclipse you can append the following snippet to the "jetty-context.xml" in "/home/.../workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmpX/contexts/appname.xml" file:
<Call name="setAttribute">
<Arg>org.eclipse.jetty.server.webapp.WebInfIncludeJarPattern</Arg>
<Arg>.*/.*myPrefixedJarToScan1-[^/]\.jar$|.*/.*myPrefixedJarToScan2-[^/]\.jar$</Arg>
</Call>