Refactor Spring Integration metrics support

Update Spring Integration metrics support since Spring Integration
`4.3.6`+ no longer needs `spring-integration-jmx` enable
`MessageChannel`, `MessageHandler` and `MessageSource` metrics.

- Add `IntegrationManagementConfiguration` conditional auto-configuration
  to provide `@EnableIntegrationManagement` when JMX is `enabled` or there
  is no `IntegrationManagementConfigurer.MANAGEMENT_CONFIGURER_NAME` bean.
  By default this bean doesn't exist and you explicitly should declare it
  (e.g. via `@EnableIntegrationManagement`) if you would like to collect
  metrics. At the same time Spring Integration enables it when JMX
  management is present (that is a purpose of that new
  `IntegrationManagementConfiguration`)

- Change `SpringIntegrationMetricReader` to read metrics from the
  `IntegrationManagementConfigurer`, not `IntegrationMBeanExporter`

- Change `PublicMetricsAutoConfiguration` to register
  `IntegrationManagementConfigurer.MANAGEMENT_CONFIGURER_NAME` bean if
  not present. Since we are here in `actuator`, therefore we are
  interested in the metrics for SI as well.

- Since we don't need JMX for the metrics any more, remove SI-JMX
  dependency from the `spring-boot-starter-integration`.

- Remove `IntegrationManagementConfiguration` modification from the
  `integrationMbeanExporter()`, since that looks like mutation of an
  external object, when end-user would prefer their own options.
  Therefore we don't need `ObjectProvider<IntegrationManagementConfigurer>`, too

- Add missed `MessageSourceMetrics` gathering for the
  `SpringIntegrationMetricReader`

Closes gh-7722

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/integration/IntegrationAutoConfiguration.java

@@ -21,8 +21,6 @@ import javax.management.MBeanServer;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
-import org.springframework.beans.factory.ObjectProvider;
-import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -35,6 +33,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.env.Environment;
 import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.config.EnableIntegrationManagement;
 import org.springframework.integration.jmx.config.EnableIntegrationMBeanExport;
 import org.springframework.integration.monitor.IntegrationMBeanExporter;
 import org.springframework.integration.support.management.IntegrationManagementConfigurer;
@@ -67,17 +66,10 @@ public class IntegrationAutoConfiguration {
 	protected static class IntegrationJmxConfiguration
 			implements EnvironmentAware, BeanFactoryAware {
 
-		private final IntegrationManagementConfigurer configurer;
-
 		private BeanFactory beanFactory;
 
 		private RelaxedPropertyResolver propertyResolver;
 
-		protected IntegrationJmxConfiguration(
-				@Qualifier(IntegrationManagementConfigurer.MANAGEMENT_CONFIGURER_NAME) ObjectProvider<IntegrationManagementConfigurer> configurerProvider) {
-			this.configurer = configurerProvider.getIfAvailable();
-		}
-
 		@Override
 		public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
 			this.beanFactory = beanFactory;
@@ -100,17 +92,25 @@ public class IntegrationAutoConfiguration {
 			if (StringUtils.hasLength(server)) {
 				exporter.setServer(this.beanFactory.getBean(server, MBeanServer.class));
 			}
-			if (this.configurer != null) {
-				if (this.configurer.getDefaultCountsEnabled() == null) {
-					this.configurer.setDefaultCountsEnabled(true);
-				}
-				if (this.configurer.getDefaultStatsEnabled() == null) {
-					this.configurer.setDefaultStatsEnabled(true);
-				}
-			}
 			return exporter;
 		}
 
 	}
 
+	@Configuration
+	@ConditionalOnClass({EnableIntegrationManagement.class, EnableIntegrationMBeanExport.class})
+	@ConditionalOnMissingBean(value = IntegrationManagementConfigurer.class,
+			name = IntegrationManagementConfigurer.MANAGEMENT_CONFIGURER_NAME,
+			search = SearchStrategy.CURRENT)
+	@ConditionalOnProperty(prefix = "spring.jmx", name = "enabled", havingValue = "true", matchIfMissing = true)
+	protected static class IntegrationManagementConfiguration {
+
+		@Configuration
+		@EnableIntegrationManagement(defaultCountsEnabled = "true", defaultStatsEnabled = "true")
+		protected static class EnableIntegrationManagementConfiguration {
+
+		}
+
+	}
+
 }

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/integration/IntegrationAutoConfigurationTests.java

@@ -31,6 +31,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
 import org.springframework.integration.support.channel.HeaderChannelRegistry;
+import org.springframework.integration.support.management.IntegrationManagementConfigurer;
 import org.springframework.jmx.export.MBeanExporter;
 import org.springframework.test.context.support.TestPropertySourceUtils;
 
@@ -86,12 +87,14 @@ public class IntegrationAutoConfigurationTests {
 		MBeanServer mBeanServer = this.context.getBean(MBeanServer.class);
 		assertDomains(mBeanServer, true, "org.springframework.integration",
 				"org.springframework.integration.monitor");
+		assertThat(this.context.getBean(IntegrationManagementConfigurer.MANAGEMENT_CONFIGURER_NAME)).isNotNull();
 	}
 
 	@Test
 	public void disableJmxIntegration() {
 		load("spring.jmx.enabled=false");
 		assertThat(this.context.getBeansOfType(MBeanServer.class)).hasSize(0);
+		assertThat(this.context.getBeansOfType(IntegrationManagementConfigurer.class)).isEmpty();
 	}
 
 	@Test