Index: trunk/src/org/openstreetmap/josm/tools/Utils.java
===================================================================
--- trunk/src/org/openstreetmap/josm/tools/Utils.java	(revision 17688)
+++ trunk/src/org/openstreetmap/josm/tools/Utils.java	(revision 17692)
@@ -1721,4 +1721,18 @@
 
     /**
+     * Determines if a class can be found for the given name.
+     * @param className class nmae to find
+     * @return {@code true} if the class can be found, {@code false} otherwise
+     * @since 17692
+     */
+    public static boolean isClassFound(String className) {
+        try {
+            return Class.forName(className) != null;
+        } catch (ClassNotFoundException e) {
+            return false;
+        }
+    }
+
+    /**
      * Determines whether JOSM has been started via Web Start (JNLP).
      * @return true if JOSM has been started via Web Start (JNLP)
@@ -1726,10 +1740,6 @@
      */
     public static boolean isRunningWebStart() {
-        try {
-            // See http://stackoverflow.com/a/16200769/2257172
-            return Class.forName("javax.jnlp.ServiceManager") != null;
-        } catch (ClassNotFoundException e) {
-            return false;
-        }
+        // See http://stackoverflow.com/a/16200769/2257172
+        return isClassFound("javax.jnlp.ServiceManager");
     }
 
@@ -1740,5 +1750,5 @@
      */
     public static boolean isRunningJavaWebStart() {
-        return isRunningWebStart() && Package.getPackage("com.sun.javaws") != null;
+        return isRunningWebStart() && isClassFound("com.sun.javaws.Main");
     }
 
@@ -1749,5 +1759,6 @@
      */
     public static boolean isRunningOpenWebStart() {
-        return isRunningWebStart() && Package.getPackage("net.adoptopenjdk.icedteaweb") != null;
+        // To be kept in sync if package name changes to org.eclipse.adoptium or something
+        return isRunningWebStart() && isClassFound("net.adoptopenjdk.icedteaweb.client.commandline.CommandLine");
     }