when sorting data overlays keep general overlays first

Closes #1895 (closed)

frontend-js/src/main/js/map/CustomMap.js

@@ -1365,21 +1365,36 @@ CustomMap.prototype.getVisibleDataOverlays = function () {
     }
   }
 
-  return Promise.all(dataOverlayPromises).then(function (overlays) {
-    overlays = overlays.filter(function (overlay) {
-      return overlay != null;
-    });
+  return Promise.all(dataOverlayPromises).then(
+    /**
+     *
+     * @param  {DataOverlay[]} overlays
+     * */
+    function (overlays) {
+
+      overlays = overlays.filter(function (overlay) {
+        return overlay != null;
+      });
 
-    overlays.sort(function (dataOverlay1, dataOverlay2) {
-      if (dataOverlay1.getOrder() < dataOverlay2.getOrder())
-        return -1;
-      if (dataOverlay1.getOrder() > dataOverlay2.getOrder())
-        return 1;
-      return 0;
-    });
 
-    return overlays;
-  });
+      overlays.sort(function (dataOverlay1, dataOverlay2) {
+        if (dataOverlay1.getPublicOverlay() === dataOverlay2.getPublicOverlay()) {
+          if (dataOverlay1.getOrder() < dataOverlay2.getOrder())
+            return -1;
+          if (dataOverlay1.getOrder() > dataOverlay2.getOrder())
+            return 1;
+          return 0;
+        } else {
+          if (dataOverlay1.getPublicOverlay() && !dataOverlay2.getPublicOverlay()) {
+            return -1;
+          } else {
+            return 1;
+          }
+        }
+      });
+
+      return overlays;
+    });
 };