Default spring.datasource.jmx-enabled to false

Change the default value of spring.datasource.jmx-enabled to false
to prevent InstanceAlreadyExistsException problems when using the
Spring Test Framework.

Fixes gh-1590

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/DataSourceAutoConfiguration.java

@@ -145,7 +145,7 @@ public class DataSourceAutoConfiguration {
 	}
 
 	@Configuration
-	@ConditionalOnProperty(prefix = "spring.datasource", name = "jmx-enabled", havingValue = "true", matchIfMissing = true)
+	@ConditionalOnProperty(prefix = "spring.datasource", name = "jmx-enabled")
 	@ConditionalOnClass(name = "org.apache.tomcat.jdbc.pool.DataSourceProxy")
 	@Conditional(DataSourceAutoConfiguration.DataSourceAvailableCondition.class)
 	@ConditionalOnMissingBean(name = "dataSourceMBean")

spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -27,7 +27,7 @@
     "name": "spring.datasource.jmx-enabled",
     "dataType": "java.lang.Boolean",
     "description": "Enables JMX support (if provided by the underlying pool).",
-    "defaultValue": true
+    "defaultValue": false
   },
   {
     "name": "spring.data.elasticsearch.repositories.enabled",

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/TomcatDataSourceConfigurationTests.java

@@ -32,6 +32,7 @@ import org.springframework.boot.test.EnvironmentTestUtils;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.EnableMBeanExport;
 import org.springframework.context.annotation.Import;
 import org.springframework.util.ReflectionUtils;
 
@@ -133,6 +134,7 @@ public class TomcatDataSourceConfigurationTests {
 
 	@Configuration
 	@Import(DataSourceAutoConfiguration.class)
+	@EnableMBeanExport
 	protected static class TomcatDataSourceConfiguration {
 
 		@Autowired