1 files changed, 31 insertions, 0 deletions
diff --git a/bundle-plugin/src/main/java/com/yahoo/container/plugin/util/Maps.java b/bundle-plugin/src/main/java/com/yahoo/container/plugin/util/Maps.java
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index 00000000000..5aa14402d4e
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+++ b/bundle-plugin/src/main/java/com/yahoo/container/plugin/util/Maps.java
@@ -0,0 +1,31 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.container.plugin.util;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.BiFunction;
+
+/**
+ * @author Tony Vaagenes
+ * @author ollivir
+ */
+public class Maps {
+    public static <K, V> Map<K, V> combine(Map<K, V> left, Map<K, V> right, BiFunction<V, V, V> combiner) {
+        Map<K, V> ret = new HashMap<>();
+        Set<K> keysRight = new HashSet<>(right.keySet());
+
+        left.forEach((k, v) -> {
+            if (keysRight.contains(k)) {
+                ret.put(k, combiner.apply(v, right.get(k)));
+                keysRight.remove(k);
+            } else {
+                ret.put(k, v);
+            }
+        });
+        keysRight.forEach(k -> ret.put(k, right.get(k)));
+
+        return ret;
+    }
+}