Remove @Primary from IntegrationMBeanExporter

Commit 3ea84f9 has wrongly introduced a `@Primary` marker on
`IntegrationMBeanExporter` so any use of both Spring's JMX support
and Spring Integration's JMX support leads to an exception. This commit
makes sure to remove the unnecessary `@Primary`

Closes gh-6328

Author: snicoll

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

@@ -33,7 +33,6 @@
 import org.springframework.context.EnvironmentAware;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.context.annotation.Primary;
 import org.springframework.core.env.Environment;
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.jmx.config.EnableIntegrationMBeanExport;
@@ -87,7 +86,6 @@ public void setEnvironment(Environment environment) {
 		}
 
 		@Bean
-		@Primary
 		public IntegrationMBeanExporter integrationMbeanExporter() {
 			IntegrationMBeanExporter exporter = new IntegrationMBeanExporter();
 			String defaultDomain = this.propertyResolver.getProperty("default-domain");

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

@@ -27,11 +27,17 @@
 import org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+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.jmx.export.MBeanExporter;
 import org.springframework.test.context.support.TestPropertySourceUtils;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertSame;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link IntegrationAutoConfiguration}.
@@ -99,6 +105,13 @@ public void customizeJmxDomain() {
 				"org.springframework.integration.monitor");
 	}
 
+	@Test
+	public void primaryExporterIsAllowed() {
+		load(CustomMBeanExporter.class);
+		assertEquals(2, this.context.getBeansOfType(MBeanExporter.class).size());
+		assertSame(this.context.getBean("myMBeanExporter"), this.context.getBean(MBeanExporter.class));
+	}
+
 	private static void assertDomains(MBeanServer mBeanServer, boolean expected,
 			String... domains) {
 		List<String> actual = Arrays.asList(mBeanServer.getDomains());
@@ -107,12 +120,30 @@ private static void assertDomains(MBeanServer mBeanServer, boolean expected,
 		}
 	}
 
-	private void load(String... environment) {
+	public void load(String... environment) {
+		load(null, environment);
+	}
+
+	private void load(Class<?> config, String... environment) {
 		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+		if (config != null) {
+			ctx.register(config);
+		}
 		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(ctx, environment);
 		ctx.register(JmxAutoConfiguration.class, IntegrationAutoConfiguration.class);
 		ctx.refresh();
 		this.context = ctx;
 	}
 
+	@Configuration
+	static class CustomMBeanExporter {
+
+		@Bean
+		@Primary
+		public MBeanExporter myMBeanExporter() {
+			return mock(MBeanExporter.class);
+		}
+
+	}
+
 }