Hi, this is not specific to Share Extras but a couple of other people have reported similar issues to me recently.
I suspect that the installers have stopped enabling the shared/lib directory in 4.2. Please check your tomcat/conf/catalina.properties file and you should have a line like
shared.loader=${catalina.home}/shared/classes,${catalina.home}/shared/lib/*.jar
If you do not have this line please add it, then the JAR files should be picked up when you restart. You will want to comment out any other lines in the file where this property is set.
Cheers,
Will