Running LS Server in Eclipse is not easy indeed, because the Server uses classloaders to decouple third party libraries, hence it is not just a matter of adding all the libraries under "Lightstreamer/lib" to the run configuration classpath.
Unfortunately, our instructions for this task, in
this thread (to which you also contributed), are obsolete and don't apply to LS 7.2.
Nevertheless, for simple scenarios in which the classloader separation is not needed, it is possible to run the Server in Eclipse by putting all jars under "Lightstreamer/lib" in the classpath. The only trick is that the libraries under the "Lightstreamer/lib/log/bridge" folder should not be included.
That said, I found your same exception when omitting the following jar from the classpath:
Lightstreamer/lib/core/javassist-3.27.0-GA.jar
so, I suppose that this jar (or perhaps the whole "Lightstreamer/lib/core" folder) is missing from your run configuration classpath.
