I have a Java project that currently has a lot of JARs in its libraries directory, which are all included in the resulting package when building. I know, however, that some
ClassPathHelper can help you with that.
Espacially the "Not on Classpath View"

This view scans for jars that are not on the classpath (but are under the current project). It provides basic browsing of packages and classes that are available but not on the classpath. This can be helpful when trying to build up a classpath, as you can quickly browse for the missing classes to see which jars contain them.