this.errorStream = errorStream;
if (extraArg == null || !(extraArg instanceof ClassType))
throw new IllegalArgumentException("No JDWP communication class found");
communicationClass = (ClassType) extraArg;
VirtualMachine vm = communicationClass.virtualMachine();
if (vm.eventRequestManager().stepRequests().size() > 0) {
throw new RuntimeException("Some threads are currently stepping");
}
if (vm.eventRequestManager().breakpointRequests().size() > 0) {
throw new RuntimeException("There are some breakpoints set");
}