#424: That worked, but maybe it is better to use the latest image.

Also reverted the slash changes.

.appveyor.yml

@@ -7,14 +7,14 @@ init:
 
 # We need at least this image to run jdk17 and jdk21 (https://www.appveyor.com/docs/windows-images-software/).
 image:
-  - Visual Studio 2019
+  - Visual Studio 2022
 
 environment:
   APPVEYOR_CACHE_ENTRY_ZIP_ARGS: -t7z -mx0 -mmt=0 -snl -snh
   MAVEN_OPTS: "-Dmaven.repo.local=C:/Users/appveyor/.m2"
   matrix:
-    - JAVA_HOME: "C:\\Program Files\\Java\\jdk17"
-    - JAVA_HOME: "C:\\Program Files\\Java\\jdk21"
+    - JAVA_HOME: "C:/Program Files/Java/jdk17"
+    - JAVA_HOME: "C:/Program Files/Java/jdk21"
 
 cache:
   - C:\Users\appveyor\.m2 -> pom.xml