The ProxyServlet should handle maps too.

src/main/java/net/sourceforge/plantuml/servlet/ProxyServlet.java

@@ -93,7 +93,12 @@ public void doGet(HttpServletRequest request, HttpServletResponse response) thro
         // generate the response
         DiagramResponse dr = new DiagramResponse(response, getOutputFormat(fmt), request);
         try {
-            dr.sendDiagram(uml, 0);
+            // special handling for the MAP since it's not using "#sendDiagram()" like the other types
+            if ("map".equals(fmt)) {
+                dr.sendMap(uml, 0);
+            } else {
+                dr.sendDiagram(uml, 0);
+            }
         } catch (IIOException e) {
             // Browser has closed the connection, so the HTTP OutputStream is closed
             // Silently catch the exception to avoid annoying log
@@ -156,6 +161,10 @@ private FileFormat getOutputFormat(String format) {
         if (format.equals("txt")) {
             return FileFormat.UTXT;
         }
+        if (format.equals("map")) {
+            return FileFormat.UTXT;
+        }
+
         return FileFormat.PNG;
     }