try to guess default crawling mode, if none set

htroot/CrawlStartExpert_p.java

@@ -99,10 +99,22 @@ public class CrawlStartExpert_p {
                 // sitemap needs "crawlingFile" parameter, checked already
                 prop.put("crawlingMode_file", "1");
                 hasMode = true;
+            } else if (crawlingMode.equalsIgnoreCase("url")
+                    && prop.getBoolean("has_crawlingURL")) {
+                prop.put("crawlingMode_url", "1");
+                hasMode = true;
             }
-            // default to URL mode
+            // try to guess mode
             if (!hasMode) {
+                if (prop.getBoolean("has_crawlingURL")) {
                     prop.put("crawlingMode_url", "1");
+                } else if (prop.getBoolean("has_sitemapURL")) {
+                    prop.put("crawlingMode_sitemap", "1");
+                } else if (prop.getBoolean("has_crawlingFile")) {
+                    prop.put("crawlingMode_file", "1");
+                } else {
+                    prop.put("crawlingMode_url", "1");
+                }
             }
         } else {
             // default to URL