DATACMNS-715 - Repository factory now adds TransactionProxy interface if available.

We now leniently add the TransactionProxy marker interface to the repository proxy to opt-out of any further transaction handling potentially applied through @EnableTransactionManagement or its XML equivalent.

The interface will be introduced in Spring 4.1.7 / 4.2 RC2 so we're reflectively adding it if present. Might be something we can think of making less indirect for Fowler once 4.1.7 has been released.

src/main/java/org/springframework/data/repository/core/support/RepositoryFactorySupport.java

@@ -60,6 +60,7 @@ public abstract class RepositoryFactorySupport implements BeanClassLoaderAware {
 
 	private static final boolean IS_JAVA_8 = org.springframework.util.ClassUtils.isPresent("java.util.Optional",
 			RepositoryFactorySupport.class.getClassLoader());
+	private static final Class<?> TRANSACTION_PROXY_TYPE = getTransactionProxyType();
 
 	private final Map<RepositoryInformationCacheKey, RepositoryInformation> repositoryInformationCache = new HashMap<RepositoryInformationCacheKey, RepositoryInformation>();
 	private final List<RepositoryProxyPostProcessor> postProcessors = new ArrayList<RepositoryProxyPostProcessor>();
@@ -187,6 +188,10 @@ public abstract class RepositoryFactorySupport implements BeanClassLoaderAware {
 		result.setTarget(target);
 		result.setInterfaces(new Class[] { repositoryInterface, Repository.class });
 
+		if (TRANSACTION_PROXY_TYPE != null) {
+			result.addInterface(TRANSACTION_PROXY_TYPE);
+		}
+
 		for (RepositoryProxyPostProcessor processor : postProcessors) {
 			processor.postProcess(result, information);
 		}
@@ -334,6 +339,21 @@ public abstract class RepositoryFactorySupport implements BeanClassLoaderAware {
 		return (R) BeanUtils.instantiateClass(constructor, constructorArguments);
 	}
 
+	/**
+	 * Returns the TransactionProxy type or {@literal null} if not on the classpath.
+	 * 
+	 * @return
+	 */
+	private static Class<?> getTransactionProxyType() {
+
+		try {
+			return org.springframework.util.ClassUtils
+					.forName("org.springframework.transaction.interceptor.TransactionalProxy", null);
+		} catch (ClassNotFoundException o_O) {
+			return null;
+		}
+	}
+
 	/**
 	 * This {@code MethodInterceptor} intercepts calls to methods of the custom implementation and delegates the to it if
 	 * configured. Furthermore it resolves method calls to finders and triggers execution of them. You can rely on having