n the target type needs to be sorted
 on multiple fields; for simple searching on multiple fields, it suffices to have independent, single-field indexes,
 which can be intersected via <a href="../util/NavigableSets.html#intersection(java.util.Collection)"><code>NavigableSets.intersection()</code></a>, etc.

 <p>
 A composite index on two fields <code>String getUsername()</code> and <code>float getBalance()</code> of type <code>User</code>
 will be represented by a <a href="Index2.html" title="interface in i