GH-9335: Fix MicrometerNodeEnhancer for a primary MeterRegistry bean

Fixes: #9335

Spring Boot provides a `CompositeMeterRegistry` bean marked with a `@Primary`.
So, this one has to be autowired whenever we would like to deal with application
environment.
The `MicrometerNodeEnhancer` has a flaw to skip `MeterRegistry` injection if we have more than one `MeterRegistry` bean.

* Fix `MicrometerNodeEnhancer` logic to use `ObjectProvider.getIfUnique()` API
which is able to deal with the `primary` properly.
Otherwise, `null` as it was before

(cherry picked from commit e0472d8)

Author: artembilan

spring-integration-core/src/main/java/org/springframework/integration/graph/MicrometerNodeEnhancer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2023 the original author or authors.
+ * Copyright 2019-2024 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.
@@ -16,7 +16,6 @@
 
 package org.springframework.integration.graph;
 
-import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
 import io.micrometer.common.docs.KeyName;
@@ -26,6 +25,7 @@
 import io.micrometer.core.instrument.search.Search;
 import io.micrometer.observation.ObservationConvention;
 
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.context.ApplicationContext;
 import org.springframework.integration.support.management.IntegrationManagement;
 import org.springframework.integration.support.management.observation.DefaultMessageReceiverObservationConvention;
@@ -58,13 +58,8 @@ public class MicrometerNodeEnhancer {
 	private final MeterRegistry registry;
 
 	MicrometerNodeEnhancer(ApplicationContext applicationContext) {
-		Map<String, MeterRegistry> registries = applicationContext.getBeansOfType(MeterRegistry.class, false, false);
-		if (registries.size() == 1) {
-			this.registry = registries.values().iterator().next();
-		}
-		else {
-			this.registry = null;
-		}
+		ObjectProvider<MeterRegistry> meterRegistryProvider = applicationContext.getBeanProvider(MeterRegistry.class);
+		this.registry = meterRegistryProvider.getIfUnique();
 	}
 
 	/**

spring-integration-core/src/test/java/org/springframework/integration/graph/IntegrationGraphServerTests.java

@@ -39,6 +39,7 @@
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.ImportResource;
 import org.springframework.context.annotation.ImportRuntimeHints;
+import org.springframework.context.annotation.Primary;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.integration.annotation.Filter;
 import org.springframework.integration.annotation.InboundChannelAdapter;
@@ -80,6 +81,7 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+import static org.mockito.Mockito.mock;
 
 /**
  * @author Gary Russell
@@ -296,10 +298,17 @@ void timersViaObservationArePopulated() {
 	public static class Config {
 
 		@Bean
+		@Primary
 		public static MeterRegistry meterRegistry() {
 			return new SimpleMeterRegistry();
 		}
 
+		// To be sure that @Primary one wins for the MicrometerNodeEnhancer
+		@Bean
+		public static MeterRegistry mockRegistry() {
+			return mock();
+		}
+
 		@Bean
 		public ObservationRegistry observationRegistry(MeterRegistry meterRegistry) {
 			ObservationRegistry registry = ObservationRegistry.create();