Error while installing the extension

[sh-o-aib]

I accurately, followed compilation steps, but while installing burpgpt-all.jar file from ./lib/build/libs/ I get folling error:

java.lang.ClassNotFoundException: burp.BurpExtender at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:476) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:589) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522) at java.base/java.lang.Class.forName0(Native Method) at java.base/java.lang.Class.forName(Class.java:398) at burp.l5y.k(Unknown Source) at burp.l5y.(Unknown Source) at burp.sg1.Z(Unknown Source) at burp.lmh.lambda$panelLoaded$0(Unknown Source) at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) at java.base/java.lang.Thread.run(Thread.java:829)