post-review changes

Author: SylvainJuge

instrumentation/jmx-metrics/library/src/test/java/io/opentelemetry/instrumentation/jmx/engine/MetricAggregationTest.java

@@ -60,6 +60,9 @@ public int getValue() {
   @RegisterExtension
   static final InstrumentationExtension testing = LibraryInstrumentationExtension.create();
 
+  // used to generate non-conflicting metric names at runtime
+  private static final AtomicInteger metricCounter = new AtomicInteger(0);
+
   private static final String DOMAIN = "otel.jmx.test";
   private static MBeanServer theServer;
 
@@ -193,8 +196,6 @@ void partialAggregateMultipleParams(MetricInfo.Type metricType) throws Exception
     }
   }
 
-  private static final AtomicInteger metricCounter = new AtomicInteger(0);
-
   private static String generateMetricName(MetricInfo.Type metricType) {
     // generate a sequential metric name that prevents naming conflicts and unexpected behaviors
     return "test.metric"