Merge pull request #11692 from izeye:null-check

* pr/11692:
  Add missing null checks and volatile keyword

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/security/reactive/ApplicationContextServerWebExchangeMatcher.java

@@ -43,9 +43,9 @@ public abstract class ApplicationContextServerWebExchangeMatcher<C>
 
 	private final Class<? extends C> contextClass;
 
-	private C context;
+	private volatile C context;
 
-	private Object contextLock = new Object();
+	private final Object contextLock = new Object();
 
 	public ApplicationContextServerWebExchangeMatcher(Class<? extends C> contextClass) {
 		Assert.notNull(contextClass, "Context class must not be null");
@@ -68,10 +68,12 @@ public abstract class ApplicationContextServerWebExchangeMatcher<C>
 	protected C getContext(ServerWebExchange exchange) {
 		if (this.context == null) {
 			synchronized (this.contextLock) {
+				if (this.context == null) {
 					this.context = createContext(exchange);
 					initialized(this.context);
 				}
 			}
+		}
 		return this.context;
 	}
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/security/servlet/ApplicationContextRequestMatcher.java

@@ -45,7 +45,7 @@ public abstract class ApplicationContextRequestMatcher<C> implements RequestMatc
 
 	private volatile C context;
 
-	private Object contextLock = new Object();
+	private final Object contextLock = new Object();
 
 	public ApplicationContextRequestMatcher(Class<? extends C> contextClass) {
 		Assert.notNull(contextClass, "Context class must not be null");
@@ -68,10 +68,12 @@ public abstract class ApplicationContextRequestMatcher<C> implements RequestMatc
 	private C getContext(HttpServletRequest request) {
 		if (this.context == null) {
 			synchronized (this.contextLock) {
+				if (this.context == null) {
 					this.context = createContext(request);
 					initialized(this.context);
 				}
 			}
+		}
 		return this.context;
 	}