Merge remote-tracking branch 'origin/master'

java/java-psi-api/src/com/intellij/psi/augment/PsiAugmentProvider.java

@@ -18,9 +18,10 @@ package com.intellij.psi.augment;
 import com.intellij.openapi.extensions.ExtensionPointName;
 import com.intellij.openapi.extensions.Extensions;
 import com.intellij.psi.PsiElement;
+import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 
@@ -32,10 +33,9 @@ public abstract class PsiAugmentProvider {
 
   @NotNull
   public static <Psi extends PsiElement> List<Psi> collectAugments(@NotNull final PsiElement element, @NotNull final Class<Psi> type) {
-    final List<Psi> augments = new ArrayList<Psi>();
+    List<Psi> augments = Collections.emptyList();
     for (PsiAugmentProvider provider : Extensions.getExtensions(EP_NAME)) {
-      final List<Psi> list = provider.getAugments(element, type);
-      augments.addAll(list);
+      augments = ContainerUtil.addAll(augments, provider.getAugments(element, type));
     }
 
     return augments;

platform/util/src/com/intellij/util/containers/ContainerUtil.java

@@ -1189,6 +1189,24 @@ public class ContainerUtil extends ContainerUtilRt {
     return findInstance(Arrays.asList(array), aClass);
   }
 
+  @NotNull
+  public static <T> List<T> addAll(@NotNull final List<T> list1, @NotNull final List<T> list2) {
+    if (list1.isEmpty() && list2.isEmpty()) {
+      return Collections.emptyList();
+    }
+    else if (list1.isEmpty()) {
+      //noinspection unchecked
+      return list2;
+    }
+    else if (list2.isEmpty()) {
+      //noinspection unchecked
+      return list1;
+    }
+
+    list1.addAll(list2);
+    return list1;
+  }
+
   @NotNull
   @Contract(pure=true)
   public static <T, V> List<T> concat(@NotNull V[] array, @NotNull Function<V, Collection<? extends T>> fun) {