Allow XADataSource auto-config with no spring.datasource properties

Fixes gh-20229

spring-boot-project/spring-boot-autoconfigure/pom.xml

@@ -877,6 +877,11 @@
 			<artifactId>transactions-jms</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>com.ibm.db2</groupId>
+			<artifactId>jcc</artifactId>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>com.jayway.jsonpath</groupId>
 			<artifactId>json-path</artifactId>

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

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -13,9 +13,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package org.springframework.boot.autoconfigure.jdbc;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import javax.sql.DataSource;
 import javax.sql.XADataSource;
 import javax.transaction.TransactionManager;
@@ -28,6 +30,7 @@ import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 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.jdbc.DataSourceProperties.DataSourceBeanCreationException;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.boot.context.properties.bind.Bindable;
 import org.springframework.boot.context.properties.bind.Binder;
@@ -102,11 +105,17 @@ public class XADataSourceAutoConfiguration implements BeanClassLoaderAware {
 	}
 
 	private ConfigurationPropertySource getBinderSource(DataSourceProperties dataSourceProperties) {
-		MapConfigurationPropertySource source = new MapConfigurationPropertySource();
-		source.put("user", dataSourceProperties.determineUsername());
-		source.put("password", dataSourceProperties.determinePassword());
-		source.put("url", dataSourceProperties.determineUrl());
-		source.putAll(dataSourceProperties.getXa().getProperties());
+		Map<Object, Object> properties = new HashMap<Object, Object>();
+		properties.putAll(dataSourceProperties.getXa().getProperties());
+		properties.computeIfAbsent("user", (key) -> dataSourceProperties.determineUsername());
+		properties.computeIfAbsent("password", (key) -> dataSourceProperties.determinePassword());
+		try {
+			properties.computeIfAbsent("url", (key) -> dataSourceProperties.determineUrl());
+		}
+		catch (DataSourceBeanCreationException ex) {
+			// Continue as not all XA DataSource's require a URL
+		}
+		MapConfigurationPropertySource source = new MapConfigurationPropertySource(properties);
 		ConfigurationPropertyNameAliases aliases = new ConfigurationPropertyNameAliases();
 		aliases.addAliases("user", "username");
 		return source.withAliases(aliases);

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

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -19,10 +19,14 @@ package org.springframework.boot.autoconfigure.jdbc;
 import javax.sql.DataSource;
 import javax.sql.XADataSource;
 
+import com.ibm.db2.jcc.DB2XADataSource;
 import org.hsqldb.jdbc.pool.JDBCXADataSource;
 import org.junit.jupiter.api.Test;
 
+import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.jdbc.XADataSourceWrapper;
+import org.springframework.boot.test.context.FilteredClassLoader;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.boot.test.util.TestPropertyValues;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
@@ -60,6 +64,20 @@ class XADataSourceAutoConfigurationTests {
 		assertThat(dataSource.getUser()).isEqualTo("un");
 	}
 
+	@Test
+	void createNonEmbeddedFromXAProperties() {
+		new ApplicationContextRunner().withConfiguration(AutoConfigurations.of(XADataSourceAutoConfiguration.class))
+				.withUserConfiguration(FromProperties.class)
+				.withClassLoader(new FilteredClassLoader("org.h2.Driver", "org.hsqldb.jdbcDriver"))
+				.withPropertyValues("spring.datasource.xa.data-source-class-name:com.ibm.db2.jcc.DB2XADataSource",
+						"spring.datasource.xa.properties.user:test", "spring.datasource.xa.properties.password:secret")
+				.run((context) -> {
+					MockXADataSourceWrapper wrapper = context.getBean(MockXADataSourceWrapper.class);
+					XADataSource xaDataSource = wrapper.getXaDataSource();
+					assertThat(xaDataSource).isInstanceOf(DB2XADataSource.class);
+				});
+	}
+
 	@Test
 	void createFromClass() throws Exception {
 		ApplicationContext context = createContext(FromProperties.class,