Generated JsonAdapter classes as @Generated and final

Author: rbygrave

jsonb-generator/src/main/java/io/avaje/jsonb/generator/SimpleAdapterWriter.java

@@ -61,7 +61,8 @@ private void writeClassEnd() {
   }
 
   private void writeClassStart() {
-    writer.append("public class %sJsonAdapter extends JsonAdapter<%s> ", adapterShortName, beanReader.shortName());
+    writer.append("@Generated").eol();
+    writer.append("public final class %sJsonAdapter extends JsonAdapter<%s> ", adapterShortName, beanReader.shortName());
     if (!beanReader.hasSubtypes()) {
       writer.append("implements ViewBuilderAware ");
     }