Tag spring.batch.job.active metric with the job name

Resolves #3750

Author: fmbenhassine

spring-batch-core/src/main/java/org/springframework/batch/core/job/AbstractJob.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2019 the original author or authors.
+ * Copyright 2006-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -301,7 +301,8 @@ public final void execute(JobExecution execution) {
 		}
 
 		JobSynchronizationManager.register(execution);
-		LongTaskTimer longTaskTimer = BatchMetrics.createLongTaskTimer("job.active", "Active jobs");
+		LongTaskTimer longTaskTimer = BatchMetrics.createLongTaskTimer("job.active", "Active jobs",
+				Tag.of("name", execution.getJobInstance().getJobName()));
 		LongTaskTimer.Sample longTaskTimerSample = longTaskTimer.start();
 		Timer.Sample timerSample = BatchMetrics.createTimerSample();
 		try {

spring-batch-samples/src/test/java/org/springframework/batch/sample/metrics/BatchMetricsTests.java

@@ -162,6 +162,7 @@ public void testBatchMetrics() throws Exception {
 
 		try {
 			Metrics.globalRegistry.get("spring.batch.job.active")
+					.tag("name", "job")
 					.longTaskTimer();
 		} catch (Exception e) {
 			fail("There should be a meter of type LONG_TASK_TIMER named spring.batch.job.active" +