Support micrometer Graphite tagsAsPrefix property

Fixes gh-11797

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/graphite/GraphiteProperties.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -67,6 +67,12 @@ public class GraphiteProperties {
 	 */
 	private GraphiteProtocol protocol;
 
+	/**
+	 * For the default naming convention, turn the specified tag keys into part of the
+	 * metric prefix.
+	 */
+	private String[] tagsAsPrefix;
+
 	public Boolean getEnabled() {
 		return this.enabled;
 	}
@@ -123,4 +129,12 @@ public class GraphiteProperties {
 		this.protocol = protocol;
 	}
 
+	public String[] getTagsAsPrefix() {
+		return this.tagsAsPrefix;
+	}
+
+	public void setTagsAsPrefix(String[] tagsAsPrefix) {
+		this.tagsAsPrefix = tagsAsPrefix;
+	}
+
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/graphite/GraphitePropertiesConfigAdapter.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -78,4 +78,10 @@ class GraphitePropertiesConfigAdapter extends PropertiesConfigAdapter<GraphitePr
 		return get(GraphiteProperties::getProtocol, GraphiteConfig.super::protocol);
 	}
 
+	@Override
+	public String[] tagsAsPrefix() {
+		return get(GraphiteProperties::getTagsAsPrefix,
+				GraphiteConfig.super::tagsAsPrefix);
+	}
+
 }