Spellchecker: (minor) @Nullable -> @NotNull

spellchecker/src/com/intellij/spellchecker/SpellCheckerManager.java

@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.spellchecker;
 
 import com.intellij.codeInsight.daemon.DaemonCodeAnalyzer;
@@ -190,7 +176,7 @@ public class SpellCheckerManager implements Disposable {
     }
   }
 
-  public void updateUserDictionary(@Nullable Collection<String> words) {
+  public void updateUserDictionary(@NotNull Collection<String> words) {
     userDictionary.replaceAll(words);
     restartInspections();
   }

spellchecker/src/com/intellij/spellchecker/settings/SpellCheckerSettingsPane.java

@@ -216,11 +216,11 @@ public class SpellCheckerSettingsPane implements Disposable {
       myListModel.removeAllElements();
     }
 
-    @Nullable
+    @NotNull
     public List<String> getWords() {
       Object[] pairs = getListItems();
       if (pairs == null) {
-        return null;
+        return new ArrayList<>();
       }
       List<String> words = new ArrayList<>();
       for (Object pair : pairs) {
@@ -232,9 +232,6 @@ public class SpellCheckerSettingsPane implements Disposable {
     public boolean isModified() {
       List<String> newWords = getWords();
       Set<String> words = manager.getUserDictionary().getEditableWords();
-      if (newWords == null) {
-        return false;
-      }
       if (newWords.size() != words.size()) {
         return true;
       }