Review fixes for avaje-jex-3.0:javaagent (open-telemetry#17269)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>

Author: otelbot[bot]

instrumentation/avaje-jex-3.0/javaagent/src/test/java/io/opentelemetry/javaagent/instrumentation/avaje/jex/v3_0/TestJexJavaApplication.java

@@ -12,7 +12,7 @@ class TestJexJavaApplication {
 
   private TestJexJavaApplication() {}
 
-  public static Server initJex() {
+  static Server initJex() {
     Jex app = Jex.create().contextPath("/test");
     app.get(
         "/param/{id}",