[SCB-2601] fix kie fileSource not support comma separated (#3122)

diff --git a/dynamic-config/config-kie/src/main/java/org/apache/servicecomb/config/kie/KieConfig.java b/dynamic-config/config-kie/src/main/java/org/apache/servicecomb/config/kie/KieConfig.java
index 7f93e1d..6409ff3 100644
--- a/dynamic-config/config-kie/src/main/java/org/apache/servicecomb/config/kie/KieConfig.java
+++ b/dynamic-config/config-kie/src/main/java/org/apache/servicecomb/config/kie/KieConfig.java
@@ -18,6 +18,7 @@
 package org.apache.servicecomb.config.kie;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
@@ -87,9 +88,7 @@
   public List<String> getFileSources() {
     Object property = finalConfig.getProperty(FILE_SOURCE);
     if (property instanceof String) {
-      List<String> result = new ArrayList<>();
-      result.add((String) property);
-      return result;
+      return new ArrayList<>(Arrays.asList(((String) property).split(",")));
     }
     if (property instanceof List) {
       return (List<String>) property;