Use a dedicated application to collect log samples

This commit moves the tasks that collect log samples for the reference
guide to an isolated application.

Closes gh-36875

Author: snicoll

spring-boot-project/spring-boot-docs/build.gradle

@@ -284,7 +284,7 @@ task runRemoteSpringApplicationExample(type: org.springframework.boot.build.docs
 
 task runSpringApplicationExample(type: org.springframework.boot.build.docs.ApplicationRunner) {
 	classpath = configurations.springApplicationExample + sourceSets.main.output
-	mainClass = "org.springframework.boot.docs.features.springapplication.MyApplication"
+	mainClass = "org.springframework.boot.docs.features.logexample.MyApplication"
 	args = ["--server.port=0"]
 	output = file("$buildDir/example-output/spring-application.txt")
 	expectedLogging = "Started MyApplication in "
@@ -293,7 +293,7 @@ task runSpringApplicationExample(type: org.springframework.boot.build.docs.Appli
 
 task runLoggingFormatExample(type: org.springframework.boot.build.docs.ApplicationRunner) {
 	classpath = configurations.springApplicationExample + sourceSets.main.output
-	mainClass = "org.springframework.boot.docs.features.springapplication.MyApplication"
+	mainClass = "org.springframework.boot.docs.features.logexample.MyApplication"
 	args = ["--spring.main.banner-mode=off", "--server.port=0"]
 	output = file("$buildDir/example-output/logging-format.txt")
 	expectedLogging = "Started MyApplication in "

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/logexample/MyApplication.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2012-2023 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.boot.docs.features.logexample;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+/**
+ * Sample application used to collect logs for the reference doc.
+ *
+ * @author Stephane Nicoll
+ */
+@SpringBootApplication
+public class MyApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(MyApplication.class, args);
+	}
+
+}