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<tr id="i5" class="rowColor">
<td class="colFirst"><code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Optional.html?is-external=true" title="class or interface in java.util" class="externalLink">Optional</a>&lt;<a href="KV.html" title="type parameter in KV">K</a>&gt;</code></td>
<th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#nullableKey()">nullableKey</a></span>()</code></th>
<td class="colLast">&nbsp;</td>
</tr>
<tr id="i6" class="alt