at java.base/java.lang.ClassLoader.loadClass (ClassLoader.java:587) at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass (LaunchedURLClassLoader.java:151) ...

It is significant that StackOverflowError ends with the word Error and is an Error (extends java.lang.Error via java.lang.VirtualMachineError) rather than a checked or runtime Exception.

Stack trace [07:48:28 ERROR]: Could not pass event InventoryCloseEvent to TestPlugin v1.0.0 java.lang.StackOverflowError: null at java.base/java.util.Objects.equals ...