I faced the same issue after import ofimporting an existing Springboot project based on JDK1.8 into SpringTestSuite4. once executed to startWhen I started the application on an embedded tomcatTomcat server, I got this error as -
"java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @140c9f39 %09"
java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @140c9f39 %09
Once I added the pre installed-installed JDK1.8 JRE from my pcPC to SpringTestSuite4 in the Installed JRE section under Window -> Preferences -> Java and made the added JRE the default. Then I clicked on applyApply and closethen Close.
It worked for me.