Review fixes for xxl-job-common:testing (#17206)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>
Co-authored-by: Trask Stalnaker <trask.stalnaker@gmail.com>

Author: otelbot[bot]

instrumentation/xxl-job/xxl-job-common/testing/src/main/java/io/opentelemetry/instrumentation/xxljob/AbstractXxlJobTest.java

@@ -95,7 +95,7 @@ protected Class<?> getReflectObjectClass() {
   }
 
   @Test
-  public void testMethodJob() {
+  void testMethodJob() {
     // method handle is null if test is not supported by tested version of the library
     Assumptions.assumeTrue(getMethodHandler() != null);
 

instrumentation/xxl-job/xxl-job-common/testing/src/main/java/io/opentelemetry/instrumentation/xxljob/ReflectiveMethodsFactory.java

@@ -35,28 +35,25 @@ static Object getTarget() {
 
   static Method getMethod() {
     try {
-      return SINGLETON_OBJECT.getClass().getMethod("echo", String.class);
+      return ReflectObject.class.getMethod("echo", String.class);
     } catch (Throwable t) {
-      // Ignore
+      return null;
     }
-    return null;
   }
 
   static Method getInitMethod() {
     try {
-      return SINGLETON_OBJECT.getClass().getMethod("initMethod");
+      return ReflectObject.class.getMethod("initMethod");
     } catch (Throwable t) {
-      // Ignore
+      return null;
     }
-    return null;
   }
 
   static Method getDestroyMethod() {
     try {
-      return SINGLETON_OBJECT.getClass().getMethod("destroyMethod");
+      return ReflectObject.class.getMethod("destroyMethod");
     } catch (Throwable t) {
-      // Ignore
+      return null;
     }
-    return null;
   }
 }