Merge pull request #9938 from Johnny Lim

* gh-9938:
  Polish

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/BackgroundPreinitializer.java

@@ -46,14 +46,14 @@ import org.springframework.http.converter.support.AllEncompassingFormHttpMessage
 public class BackgroundPreinitializer
 		implements ApplicationListener<SpringApplicationEvent> {
 
-	private static final AtomicBoolean preinitalizationStarted = new AtomicBoolean(false);
+	private static final AtomicBoolean preinitializationStarted = new AtomicBoolean(false);
 
 	private static final CountDownLatch preinitializationComplete = new CountDownLatch(1);
 
 	@Override
 	public void onApplicationEvent(SpringApplicationEvent event) {
 		if (event instanceof ApplicationEnvironmentPreparedEvent) {
-			if (preinitalizationStarted.compareAndSet(false, true)) {
+			if (preinitializationStarted.compareAndSet(false, true)) {
 				performPreinitialization();
 			}
 		}

spring-boot-docs/src/main/asciidoc/deployment.adoc

@@ -451,7 +451,7 @@ then use the https://cloud.google.com/sdk/downloads[Google Cloud SDK] to push yo
 Spring Boot app into that slot from the command line or CI build.
 
 App Engine needs you to create an `app.yaml` file to describe the resources your app
-requires. Normally you put this in `src/min/appengine`, and it looks something like this:
+requires. Normally you put this in `src/main/appengine`, and it looks something like this:
 
 [source,yaml,indent=0]
 ----

spring-boot-docs/src/main/asciidoc/using-spring-boot.adoc

@@ -882,7 +882,7 @@ however it doesn't support as many frameworks and it isn't commercially supporte
 ==== Excluding resources
 Certain resources don't necessarily need to trigger a restart when they are changed. For
 example, Thymeleaf templates can just be edited in-place. By default changing resources
-in `/META-INF/maven`, `/META-INF/resources` ,`/resources` ,`/static` ,`/public` or
+in `/META-INF/maven`, `/META-INF/resources`, `/resources`, `/static`, `/public` or
 `/templates` will not trigger a restart but will trigger a
 <<using-boot-devtools-livereload, live reload>>. If you want to customize these exclusions
 you can use the `spring.devtools.restart.exclude` property. For example, to exclude only

spring-boot/src/main/java/org/springframework/boot/type/classreading/ConcurrentReferenceCachingMetadataReaderFactory.java

@@ -29,7 +29,7 @@ import org.springframework.util.ConcurrentReferenceHashMap;
 
 /**
  * Caching implementation of the {@link MetadataReaderFactory} interface backed by a
- * {@link ConcurrentReferenceHashMap} , caching {@link MetadataReader} per Spring
+ * {@link ConcurrentReferenceHashMap}, caching {@link MetadataReader} per Spring
  * {@link Resource} handle (i.e. per ".class" file).
  *
  * @author Phillip Webb