Sorting MultiValueMap
<p>I want to sort MultiValueMap by key.</p>

<pre><code>[[AdGenres-b:key:[177, 184],
 MusicalStyles-b:key:[30],
 SongTitle:[What I've Done],
 ArtistName:[Linkin Park],
 MusicVideoRating:[TV-14],
 MusicalStyles-b:value:[Rock],
 PlayId:[1367],
 AdGenres-b:value:[Rock - Rock, Rock - Alternative],
 MusicVideoProvider:[Warner Music Group], AssetId:[91744]], 
[[AdGenres-b:key:[177, 184],
 MusicalStyles-b:key:[30],
 SongTitle:[What I've Done],
 ArtistName:[Linkin Park],
 MusicVideoRating:[TV-14],
 MusicalStyles-b:value:[Rock],
 PlayId:[1360],
 AdGenres-b:value:[Rock - Rock, Rock - Alternative],
 MusicVideoProvider:[Warner Music Group], AssetId:[91740]]
</code></pre>

<p>Here I want to sort by PlayId and place them back in sorted order </p>
