Guard IntegrationJmxConfiguration if no mBeanServer is available

Closes gh-12966

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

 /*
- * Copyright 2012-2016 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.
@@ -22,6 +22,7 @@ import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
@@ -70,6 +71,7 @@ public class IntegrationAutoConfiguration {
 	@Configuration
 	@ConditionalOnClass(EnableIntegrationMBeanExport.class)
 	@ConditionalOnMissingBean(value = IntegrationMBeanExporter.class, search = SearchStrategy.CURRENT)
+	@ConditionalOnBean(MBeanServer.class)
 	@ConditionalOnProperty(prefix = "spring.jmx", name = "enabled", havingValue = "true", matchIfMissing = true)
 	protected static class IntegrationJmxConfiguration
 			implements EnvironmentAware, BeanFactoryAware {

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

 /*
- * Copyright 2012-2016 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.
@@ -82,6 +82,16 @@ public class IntegrationAutoConfigurationTests {
 						.isEmpty();
 	}
 
+	@Test
+	public void noMBeanServerAvailable() {
+		this.context = new AnnotationConfigApplicationContext();
+		this.context.register(IntegrationAutoConfiguration.class);
+		this.context.refresh();
+		assertThat(this.context.getBean(TestGateway.class)).isNotNull();
+		assertThat(this.context.getBean(IntegrationComponentScanAutoConfiguration.class))
+				.isNotNull();
+	}
+
 	@Test
 	public void parentContext() {
 		load();