[ZEPPELIN-6529] Evict note cache entries when removing a folder

zeppelin-server/src/main/java/org/apache/zeppelin/notebook/NoteManager.java

@@ -305,9 +305,10 @@ public List<NoteInfo> removeFolder(String folderPath, AuthenticationInfo subject
     Folder folder = getFolder(folderPath);
     List<NoteInfo> noteInfos = folder.getParent().removeFolder(folder.getName(), subject);
 
-    // update notesInfo
+    // update notesInfo and evict the deleted notes from the cache, mirroring removeNote
     for (NoteInfo noteInfo : noteInfos) {
       this.notesInfo.remove(noteInfo.getId());
+      this.noteCache.removeNote(noteInfo.getId());
     }
 
     return noteInfos;

zeppelin-server/src/test/java/org/apache/zeppelin/notebook/NoteManagerTest.java

@@ -174,6 +174,20 @@ void testLruCache() throws IOException {
     assertTrue(noteManager.containsNote(noteNew3.getPath()));
   }
 
+  @Test
+  void testRemoveFolderEvictsNoteCache() throws IOException {
+    // add 2 notes under the same folder
+    Note note1 = createNote("/folder1/note1");
+    Note note2 = createNote("/folder1/note2");
+    noteManager.addNote(note1, AuthenticationInfo.ANONYMOUS);
+    noteManager.addNote(note2, AuthenticationInfo.ANONYMOUS);
+    assertEquals(2, noteManager.getCacheSize());
+
+    // remove folder should evict its notes from the cache as well
+    noteManager.removeFolder("/folder1", AuthenticationInfo.ANONYMOUS);
+    assertEquals(0, noteManager.getCacheSize());
+  }
+
   @Test
   void testConcurrentOperation() throws Exception {
     int threshold = 10, noteNum = 150;