 interface in java.util"><code>Set</code></a> or <a href="https://docs.oracle.com/javase/8/docs/api/java/util/SortedSet.html?is-external=true" title="class or interface in java.util"><code>SortedSet</code></a> then the resulting collection
 will have a single entry mapped from the supplied default value.
 </p>
 <p>
 If this annotation is not used and the corresponding meta-data is not
 present in the request, the value will be an empty collection for
 <code>List</code>, <code>Set</code> or <code>SortedSet</