a href="https://docs.oracle.com/javase/8/docs/api/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>&nbsp;id,
 <a href="CommandCompletions.CommandCompletionHandler.html" title="interface in co.aikar.commands">CommandCompletions.CommandCompletionHandler</a>&lt;<a href="CommandCompletions.html" title="type parameter in CommandCompletions">C</a>&gt;&nbsp;handler)</span></div>
<div class="block">Registr a completion handler to provide command completions based on the