title: How to convert the values of a Map of List to a single List
body: <p>How is the best (efficient and simple) way to convert the values of a <code>Map&lt;Object1, List&lt;Object2&gt;&gt;</code> to a <code>List&lt;Object2&gt;</code>. Should I simply iterate over all entries and <code>adAll</code> the items to a list?</p>