How nice would 'Map.getAsOptional' be?

MapGet.java

package org.codefx.lab.optional;

import java.text.MessageFormat;
import java.util.HashMap;
import java.util.Map;
import java.util.Optional;

public class MapGet {

	private final MapWithGetAsOptional<Integer, String> map = new HashMapWithGetAsOptional<>();

	public Optional<MessageFormat> getFormat_if(int index) {
		if(map.containsKey(index))
			return Optional.of(new MessageFormat(map.get(index)));
		else
			return Optional.empty();
	}

	public Optional<MessageFormat> getFormat_ternary(int index) {
		return map.containsKey(index)
				? Optional.of(new MessageFormat(map.get(index)))
				: Optional.empty();
	}

	public Optional<MessageFormat> getFormat_optionalOf(int index) {
		return Optional.ofNullable(map.get(index))
				.map(MessageFormat::new);
	}

	public Optional<MessageFormat> getFormat_optional(int index) {
		return map.getAsOptional(index)
				.map(MessageFormat::new);
	}

	interface MapWithGetAsOptional<K, V> extends Map<K, V> {

		default Optional<V> getAsOptional(Object key) {
			return Optional.ofNullable(get(key));
		}

	}

	class HashMapWithGetAsOptional<K, V> extends HashMap<K, V> implements MapWithGetAsOptional<K, V> {
		// nothing to do here
	}

}