add a Multimap implementation

impl/src/main/java/org/jboss/weld/extensions/util/collections/AbstractMapEntry.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2007 Google Inc.
+ *
+ * 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.
+ */
+
+package org.jboss.weld.extensions.util.collections;
+
+import java.util.Map.Entry;
+
+/**
+ * Implementation of the {@code equals}, {@code hashCode}, and {@code toString}
+ * methods of {@code Entry}.
+ *
+ * @author Jared Levy
+ */
+abstract class AbstractMapEntry<K, V> implements Entry<K, V> {
+
+  public abstract K getKey();
+
+  public abstract V getValue();
+
+  public V setValue(V value) {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override public boolean equals(Object object) {
+    if (object instanceof Entry<?, ?>) {
+      Entry<?, ?> that = (Entry<?, ?>) object;
+      return Objects.equal(this.getKey(), that.getKey())
+          && Objects.equal(this.getValue(), that.getValue());
+    }
+    return false;
+  }
+
+  @Override public int hashCode() {
+    K k = getKey();
+    V v = getValue();
+    return ((k == null) ? 0 : k.hashCode()) ^ ((v == null) ? 0 : v.hashCode());
+  }
+
+  /**
+   * Returns a string representation of the form <code>{key}={value}</code>.
+   */
+  @Override public String toString() {
+    return getKey() + "=" + getValue();
+  }
+}