lamda-gauge-example.patch

diff --git a/src/test/java/org/apache/sling/commons/metrics/internal/MetricServiceTest.java b/src/test/java/org/apache/sling/commons/metrics/internal/MetricServiceTest.java
index a8af34a..ad0db8c 100644
--- a/src/test/java/org/apache/sling/commons/metrics/internal/MetricServiceTest.java
+++ b/src/test/java/org/apache/sling/commons/metrics/internal/MetricServiceTest.java
@@ -22,6 +22,8 @@ package org.apache.sling.commons.metrics.internal;
 import java.lang.management.ManagementFactory;
 import java.util.Collections;
 import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import javax.management.MBeanServer;
 import javax.management.ObjectName;
@@ -163,6 +165,23 @@ public class MetricServiceTest {
         assertFalse(getRegistry().getGauges().containsKey("foo"));
     }
 
+    @Test
+    public void lambdaGaugeExample() {
+        activate();
+        final AtomicInteger value = new AtomicInteger(451);
+        final String name = "Gauge_" + UUID.randomUUID();
+        getRegistry().register(name, (com.codahale.metrics.Gauge<Integer>) () -> value.get());
+        try {
+            assertEquals(451, getRegistry().getGauges().get(name).getValue());
+            value.incrementAndGet();
+            assertEquals(452, getRegistry().getGauges().get(name).getValue());
+        } finally {
+            assertTrue(getRegistry().getGauges().containsKey(name));
+            getRegistry().remove(name);
+            assertFalse(getRegistry().getGauges().containsKey(name));
+        }
+    }
+
     private MetricRegistry getRegistry(){
         return context.getService(MetricRegistry.class);
     }