When running a java application with the options
    "-javaagent:myagent.jar -Djava.system.classloader=MyClassLoader",
  myagent.jar is added to the custom system class loader rather
  than the application class loader.
 
  In addition, the java.lang.instrument package description has a small
  update making it clear that a custom system class loader needs to define
  appendToClassPathForInstrumentation in order to load the agent at startup.
  Before custom system class loaders were required to implement this method
  only if the agents are started in the live phase (Agent_OnAttach).