Update javaagent-tooling/javaagent-tooling-java9/src/main/java/io/opentelemetry/javaagent/tooling/ModuleOpener.java

Co-authored-by: SylvainJuge <[email protected]>

Author: laurit

javaagent-tooling/javaagent-tooling-java9/src/main/java/io/opentelemetry/javaagent/tooling/ModuleOpener.java

@@ -46,7 +46,7 @@ private ModuleOpener() {}
   public static void open(
       Instrumentation instrumentation,
       JavaModule targetModule,
-      ClassLoader openTo,
+      @Nullable ClassLoader openTo,
       Collection<String> packagesToOpen) {
 
     JavaModule openToModule =