Fixed a problem with example code in article "Letting The User Download A File" (#11971)

Fixes #10580

1 files changed, 9 insertions, 2 deletions

diff --git a/documentation/articles/LettingTheUserDownloadAFile.asciidoc b/documentation/articles/LettingTheUserDownloadAFile.asciidoc
index f977b07956..1ede8bd5c0 100644
--- a/documentation/articles/LettingTheUserDownloadAFile.asciidoc
+++ b/documentation/articles/LettingTheUserDownloadAFile.asciidoc
@@ -104,8 +104,15 @@ public class OnDemandFileDownloader extends FileDownloader {
     return super.handleConnectorRequest(request, response, path);
   }
 
-  private StreamResource getResource () {
-    return (StreamResource) this.getResource("dl");
+  private StreamResource getResource() {
+    StreamResource result = null;
+    this.getSession().lock();
+    try {
+      result = (StreamResource) this.getResource("dl");
+    } finally {
+      this.getSession().unlock();
+    }
+    return result;
   }
 }
 ....