Steps to reproduce the issue

Setup

1. Build the JMC agent

Steps

1. Run  InstrumentedClass.java using JDK 11 with VM Argument --add-opens java.base/jdk.internal.misc=ALL-UNNAMED
2. From JMC, Import events.xml (Window -> Agent Preset Manager) 
3. From JMC - JVM Browser -> Open JMC Agent Plugin window
   1. Browse agent.jar built as part of the setup above
   2. Browse events.xml
   3. Start Agent Plugin
4. perform a flight recording of InstrumentedClass and verify from the resulting JFR, that the injected events are available in the JFR 
5. From the agent plugin page, click on load a preset ( ) and select the events.xml (No difference to the event definitions in the XML, this could be a negative scenario as well. but it can be extrapolated as probing from multiple JVM connections)
6. JMC agent attempts to re-inject the events to the running JVM and it crashes.

Attached are 

1. Core dump of target JVM (ie InstrumentedClass) : hs_err_pid48451.log
2. Terminal Log for InstrumentedClass : TerminalOutput.log
3. JMC Log : JMC.log