diff --git a/doc/doc-server/src/main/java/cn/axzo/nanopart/doc/file/index/IndexSupport.java b/doc/doc-server/src/main/java/cn/axzo/nanopart/doc/file/index/IndexSupport.java
index 9b8e89aa..a8f61524 100644
--- a/doc/doc-server/src/main/java/cn/axzo/nanopart/doc/file/index/IndexSupport.java
+++ b/doc/doc-server/src/main/java/cn/axzo/nanopart/doc/file/index/IndexSupport.java
@@ -132,6 +132,7 @@ public class IndexSupport {
 
 	void ensureChildNameNotUsed(IndexNodeParentScope parentScope, IndexNodeType nodeType, String childName) {
 		IndexNode child = indexNodeDao.findValidChildByName(parentScope, nodeType, childName);
+		// don't use BizAssertions.assertNull
 		if (child != null)
 			throw new NameUsedException("名称已被使用");
 	}