fixed some structure bugs in java skill tree

data/1.Java初阶/10.类和接口/2.抽象类/abstract.json

@@ -2,5 +2,6 @@
   "type": "code_options",
   "author": "ccat",
   "source": "abstract.md",
-    "notebook_enable": false
+  "notebook_enable": false,
+  "exercise_id": "b45114a920ac464292259fe5f33c925b"
 }
\ No newline at end of file

data/1.Java初阶/10.类和接口/2.抽象类/config.json

@@ -5,5 +5,6 @@
     "接口"
   ],
   "children": [],
-  "node_id": "java-968fb08ea9294e3c99aab38cbfe916cb"
+  "node_id": "java-968fb08ea9294e3c99aab38cbfe916cb",
+  "export": ["abstract.json"]
 }
\ No newline at end of file