VIEWERJAVA-3273 - Cannot enter synchronized block because the return value is null

Author: oleksii-unnamed

README.md

@@ -21,7 +21,7 @@ User Interface for GroupDocs.Viewer for Java. API for easily integrating a docum
       <dependency>
         <groupId>com.groupdocs</groupId>
         <artifactId>groupdocs-viewer-ui</artifactId>
-        <version>23.7</version>
+        <version>23.7.1</version>
       </dependency>
 
       <dependency>

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>com.groupdocs</groupId>
     <artifactId>groupdocs-viewer-ui</artifactId>
-    <version>23.7</version>
+    <version>23.7.1</version>
     <packaging>jar</packaging>
 
     <name>GroupDocs.Viewer for Java User Interface</name>

res/simplified-pom.xml

@@ -6,7 +6,7 @@
     <artifactId>groupdocs-viewer-ui</artifactId>
     <name>GroupDocs.Viewer for Java User Interface</name>
     <url>https://github.com/groupdocs-viewer/GroupDocs.Viewer-for-Java-UI</url>
-    <version>23.7</version>
+    <version>23.7.1</version>
     <description>
         GroupDocs.Viewer UI is a rich UI interface that designed to work in conjunction with GroupDocs.Viewer for Java to display most popular file and document formats in a browser.
         To integrate GroupDocs.Viewer UI in your Java project you just need to configure Viewer API and handle requests using specific endpoint handler provided in GroupDocs.Viewer.UI.

samples/groupdocs-viewer-java-ui-spring-boot/pom.xml

@@ -31,7 +31,7 @@
 		<dependency>
 			<groupId>com.groupdocs</groupId>
 			<artifactId>groupdocs-viewer-ui</artifactId>
-			<version>23.7</version>
+			<version>23.7.1</version>
 		</dependency>
 
 		<dependency>

src/main/java/com/groupdocs/viewerui/ui/api/viewer/BaseViewer.java

@@ -196,7 +196,8 @@ private Page renderPageInternal(Viewer viewer, FileCredentials fileCredentials,
 
 	private static synchronized Object getFileLock(String filename) {
 		final Object lock = new Object();
-		return _asyncLock.computeIfAbsent(filename, k -> new WeakReference<>(lock)).get(); // Retrieve the actual lock object
+		final Object actualLock = _asyncLock.computeIfAbsent(filename, k -> new WeakReference<>(lock)).get();// Retrieve the actual lock object
+		return actualLock == null ? lock : actualLock;
 	}
 
 	private static void cleanupUnusedLocks() {

src/main/java/com/groupdocs/viewerui/ui/core/caching/CachingViewer.java

@@ -209,7 +209,8 @@ private static void synchronizedBlock(String fileName, Runnable synchronizedBloc
 
     private static synchronized Object getFileLock(String filename) {
         final Object lock = new Object();
-        return _asyncLock.computeIfAbsent(filename, k -> new WeakReference<>(lock)).get(); // Retrieve the actual lock object
+        final Object actualLock = _asyncLock.computeIfAbsent(filename, k -> new WeakReference<>(lock)).get(); // Retrieve the actual lock object
+        return actualLock == null ? lock : actualLock;
     }
 
     private static void cleanupUnusedLocks() {