use consistent prefix for memory pool metrics

Author: fstab

simpleclient_hotspot/src/main/java/io/prometheus/client/hotspot/MemoryPoolsExports.java

@@ -49,7 +49,7 @@ void addMemoryAreaMetrics(List<MetricFamilySamples> sampleFamilies) {
     MemoryUsage nonHeapUsage = memoryBean.getNonHeapMemoryUsage();
 
     GaugeMetricFamily finalizer = new GaugeMetricFamily(
-        "jvm_objects_pending_finalization",
+        "jvm_memory_objects_pending_finalization",
         "The number of objects waiting in the finalizer queue.",
         memoryBean.getObjectPendingFinalizationCount());
     sampleFamilies.add(finalizer);

simpleclient_hotspot/src/test/java/io/prometheus/client/hotspot/MemoryPoolsExportsTest.java

@@ -178,7 +178,7 @@ public void testMemoryAreas() {
     assertEquals(
         10L,
         registry.getSampleValue(
-            "jvm_objects_pending_finalization"),
+            "jvm_memory_objects_pending_finalization"),
         .0000001);
     assertEquals(
         500000L,