Avoid ClassCastException (apache#239)

Author: thomasleplus

dubbo-admin/src/main/java/com/alibaba/dubbo/governance/web/common/interceptor/RestfuleUrlRewriter.java

@@ -101,7 +101,7 @@ public void postSubstitution(RewriteSubstitutionContext context) {
             return;
         }
         //兼容包含group的path
-        String[] split = (String[]) temp.toArray();
+        String[] split = (String[]) temp.toArray(new String[temp.size()]);
 
         if(temp.size()>2&&temp.contains("services")){
             List<String> parts = new ArrayList<String>();