Add CoroutinesAnnotationTransactionInterceptorTests

suspendingValueSuccess() currently fails due to an
unexpected rollback on transactional suspending functions
returning a value.

See gh-25998

spring-tx/src/test/kotlin/org/springframework/transaction/annotation/CoroutinesAnnotationTransactionInterceptorTests.kt

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2002-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package org.springframework.transaction.annotation
 
 import kotlinx.coroutines.delay
@@ -11,6 +27,9 @@ import org.springframework.transaction.interceptor.TransactionInterceptor
 import org.springframework.transaction.testfixture.CallCountingTransactionManager
 import org.springframework.transaction.testfixture.ReactiveCallCountingTransactionManager
 
+/**
+ * @author Sebastien Deleuze
+ */
 class CoroutinesAnnotationTransactionInterceptorTests {
 
 	private val ptm = CallCountingTransactionManager()