From 2255c3bfcf108f95f00724072c4386bb5b391ac1 Mon Sep 17 00:00:00 2001
From: Dmitry Batkovich <dmitry.batkovich@jetbrains.com>
Date: Thu, 8 Jun 2017 14:45:32 +0300
Subject: [PATCH] relevant method chain completion: don't add items to
 unmodifiable collection (EA-102737)

---
 .../intellij/compiler/chainsSearch/ChainSearcher.java | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/java/compiler/impl/src/com/intellij/compiler/chainsSearch/ChainSearcher.java b/java/compiler/impl/src/com/intellij/compiler/chainsSearch/ChainSearcher.java
index a741b77035eb..d2afd2168294 100644
--- a/java/compiler/impl/src/com/intellij/compiler/chainsSearch/ChainSearcher.java
+++ b/java/compiler/impl/src/com/intellij/compiler/chainsSearch/ChainSearcher.java
@@ -48,7 +48,7 @@ public class ChainSearcher {
       if (methods == null) {
         methods = currentMethods;
       } else {
-        methods.addAll(currentMethods);
+        methods = unionSortedSet(currentMethods, methods);
       }
     }
     return new SearchInitializer(methods, context);
@@ -169,4 +169,13 @@ public class ChainSearcher {
       result.add(newChain);
     }
   }
+
+  private static <T> SortedSet<T> unionSortedSet(SortedSet<T> s1, SortedSet<T> s2) {
+    if (s1.isEmpty()) return s2;
+    if (s2.isEmpty()) return s1;
+    TreeSet<T> result = new TreeSet<>();
+    result.addAll(s1);
+    result.addAll(s2);
+    return result;
+  }
 }
\ No newline at end of file