Before you start the application server, enable remote debugging by updating standalone.conf (in wildfly/bin folder). You should uncomment the line that contains the following. By uncomment, I mean remove the "#" which you probably already knew.

#JAVA_OPTS="$JAVA_OPTS -agentlib:jdwp=transport=dt_socket,address=8787,server=y,suspend=n"

When you start the WildFly application server, it will allow remote debuggers to attach. Be sure to comment again after your done.