Supports CTR section of the dataflow.spring.io

resolves another part of #180

It is associated with PR https://github.com/spring-io/dataflow.spring.io/pull/188

transition-sample/src/test/java/io/spring/taskapp/TaskappApplicationTests.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 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
+ *
+ *          http://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 io.spring.taskapp;
+
+import org.junit.Rule;
+import org.junit.Test;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.test.system.OutputCaptureRule;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class TaskappApplicationTests {
+
+	@Rule
+	public OutputCaptureRule outputCapture = new OutputCaptureRule();
+
+	@Test
+	public void contextLoads() {
+		String[] args = {"--taskapp.exitMessage=FOO"};
+		SpringApplication.run(TaskappApplication.class, args);
+
+		String output = this.outputCapture.toString();
+		assertThat(output).contains(" exitMessage='FOO', errorMessage='null'");
+	}
+
+}