diff -r 5bce1b7e7800 -r 47f19ff9903c src/jdk.internal.vm.compiler/share/classes/org.graalvm.collections/src/org/graalvm/collections/UnmodifiableEconomicMap.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.collections/src/org/graalvm/collections/UnmodifiableEconomicMap.java	Fri Feb 02 17:28:17 2018 -0800
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2017, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.graalvm.collections;
+
+/**
+ * Unmodifiable memory efficient map data structure.
+ *
+ * @since 1.0
+ */
+public interface UnmodifiableEconomicMap<K, V> {
+
+    /**
+     * Returns the value to which {@code key} is mapped, or {@code null} if this map contains no
+     * mapping for {@code key}.
+     *
+     * @since 1.0
+     */
+    V get(K key);
+
+    /**
+     * Returns the value to which {@code key} is mapped, or {@code defaultValue} if this map
+     * contains no mapping for {@code key}.
+     *
+     * @since 1.0
+     */
+    default V get(K key, V defaultValue) {
+        V v = get(key);
+        if (v == null) {
+            return defaultValue;
+        }
+        return v;
+    }
+
+    /**
+     * Returns {@code true} if this map contains a mapping for {@code key}.
+     *
+     * @since 1.0
+     */
+    boolean containsKey(K key);
+
+    /**
+     * Returns the number of key-value mappings in this map.
+     *
+     * @since 1.0
+     */
+    int size();
+
+    /**
+     * Returns {@code true} if this map contains no key-value mappings.
+     *
+     * @since 1.0
+     */
+    boolean isEmpty();
+
+    /**
+     * Returns a {@link Iterable} view of the values contained in this map.
+     *
+     * @since 1.0
+     */
+    Iterable<V> getValues();
+
+    /**
+     * Returns a {@link Iterable} view of the keys contained in this map.
+     *
+     * @since 1.0
+     */
+    Iterable<K> getKeys();
+
+    /**
+     * Returns a {@link UnmodifiableMapCursor} view of the mappings contained in this map.
+     *
+     * @since 1.0
+     */
+    UnmodifiableMapCursor<K, V> getEntries();
+}