STDERR:
java.lang.ClassCastException: Keys and values in Properties must be Strings
at java.base/jdk.internal.util.xml.PropertiesDefaultHandler.store(PropertiesDefaultHandler.java:122)
at java.base/java.util.Properties.storeToXML(Properties.java:1107)
at java.base/java.util.Properties.storeToXML(Properties.java:1007)
at LoadAndStoreXMLWithDefaults.writeToXML(LoadAndStoreXMLWithDefaults.java:40)
at LoadAndStoreXMLWithDefaults.main(LoadAndStoreXMLWithDefaults.java:85)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:298)
at java.base/java.lang.Thread.run(Thread.java:832)