This directory contains the libs used for compiling the
j4p-agent. servlet-api-2.4.jar is used for building
only, whereas json_simple-1.1.jar is the JSON support library which
gets bundled within j4p.war 

servlet-api-2.4.jar is provided by Sun(TM) and are
distributed under the GPL. You can find them within the JEE 5
specification, e.g. bundled along with Glassfish 2 
(https://glassfish.dev.java.net/downloads/v2ur2-b04.html)

json-simple's is distributed under the Apache License V2 and can be
found at http://code.google.com/p/json-simple/