An implementation of Java's AbstractMap that returns the same value for all keys.

SingleValueMap.java

package com.amazonaws.ec2.tagging.util;

import java.util.AbstractMap;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;
import java.util.stream.Collectors;

public class SingleValueMap<K, V> extends AbstractMap<K, V> {

    private final Set<K> keys;
    private final V value;

    public SingleValueMap(final Collection<K> keys, final V value) {
        this.keys = new HashSet<>(keys);
        this.value = value;
    }

    @Override
    public Set<Entry<K, V>> entrySet() {
        return keys.stream()
                .map(key -> new AbstractMap.SimpleImmutableEntry<K, V>(key, this.value))
                .collect(Collectors.toSet());
    }
}