Make MetricsProperties fields final if possible

Closes gh-13324

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsProperties.java

@@ -20,7 +20,6 @@ import java.util.LinkedHashMap;
 import java.util.Map;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
-import org.springframework.util.Assert;
 
 /**
  * {@link ConfigurationProperties} for configuring Micrometer-based metrics.
@@ -42,7 +41,7 @@ public class MetricsProperties {
 	 * Whether meter IDs starting-with the specified name should be enabled. The longest
 	 * match wins, the key `all` can also be used to configure all meters.
 	 */
-	private Map<String, Boolean> enable = new LinkedHashMap<>();
+	private final Map<String, Boolean> enable = new LinkedHashMap<>();
 
 	/**
 	 * Common tags that are applied to every meter.
@@ -65,11 +64,6 @@ public class MetricsProperties {
 		return this.enable;
 	}
 
-	public void setEnable(Map<String, Boolean> enable) {
-		Assert.notNull(enable, "enable must not be null");
-		this.enable = enable;
-	}
-
 	public Map<String, String> getTags() {
 		return this.tags;
 	}
@@ -172,14 +166,14 @@ public class MetricsProperties {
 		 * this has no effect. The longest match wins, the key `all` can also be used to
 		 * configure all meters.
 		 */
-		private Map<String, Boolean> percentilesHistogram = new LinkedHashMap<>();
+		private final Map<String, Boolean> percentilesHistogram = new LinkedHashMap<>();
 
 		/**
 		 * Specific computed non-aggregable percentiles to ship to the backend for meter
 		 * IDs starting-with the specified name. The longest match wins, the key `all` can
 		 * also be used to configure all meters.
 		 */
-		private Map<String, double[]> percentiles = new LinkedHashMap<>();
+		private final Map<String, double[]> percentiles = new LinkedHashMap<>();
 
 		/**
 		 * Specific SLA boundaries for meter IDs starting-with the specified name. The
@@ -188,35 +182,20 @@ public class MetricsProperties {
 		 * as a long or as a Duration value (for timer meters, defaulting to ms if no unit
 		 * specified).
 		 */
-		private Map<String, ServiceLevelAgreementBoundary[]> sla = new LinkedHashMap<>();
+		private final Map<String, ServiceLevelAgreementBoundary[]> sla = new LinkedHashMap<>();
 
 		public Map<String, Boolean> getPercentilesHistogram() {
 			return this.percentilesHistogram;
 		}
 
-		public void setPercentilesHistogram(Map<String, Boolean> percentilesHistogram) {
-			Assert.notNull(percentilesHistogram, "PercentilesHistogram must not be null");
-			this.percentilesHistogram = percentilesHistogram;
-		}
-
 		public Map<String, double[]> getPercentiles() {
 			return this.percentiles;
 		}
 
-		public void setPercentiles(Map<String, double[]> percentiles) {
-			Assert.notNull(percentiles, "Percentiles must not be null");
-			this.percentiles = percentiles;
-		}
-
 		public Map<String, ServiceLevelAgreementBoundary[]> getSla() {
 			return this.sla;
 		}
 
-		public void setSla(Map<String, ServiceLevelAgreementBoundary[]> sla) {
-			Assert.notNull(sla, "SLA must not be null");
-			this.sla = sla;
-		}
-
 	}
 
 }