<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have searched the <a href="https://github.com/apache/dubbo/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have checked the <a href="https://github.com/apache/dubbo/blob/master/FAQ.md">FAQ</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h3 dir="auto">Environment</h3>
<ul dir="auto">
<li>Dubbo version: xxx</li>
<li>Operating System version: xxx</li>
<li>Java version: xxx</li>
</ul>
<h3 dir="auto">Steps to reproduce this issue</h3>
<p dir="auto">unboxing may get failed because null value could be returned<br>
<a href="https://github.com/apache/dubbo/blob/master/dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/ServiceDiscoveryRegistry.java#L587">https://github.com/apache/dubbo/blob/master/dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/ServiceDiscoveryRegistry.java#L587</a></p>
<p dir="auto">Pls. provide [GitHub address] to reproduce this issue.</p>
<h3 dir="auto">Expected Result</h3>
<p dir="auto">What do you expected from the above steps？</p>
<h3 dir="auto">Actual Result</h3>
<p dir="auto">What actually happens?</p>
<p dir="auto">If there is an exception, please attach the exception trace:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Just put your stack trace here!"><pre class="notranslate"><code class="notranslate">Just put your stack trace here!
</code></pre></div>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have searched the <a href="https://github.com/apache/dubbo/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the <a href="https://github.com/apache/dubbo/blob/master/FAQ.md">FAQ</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h3 dir="auto">Environment</h3>
<ul dir="auto">
<li>Dubbo version: master</li>
<li>Operating System version: all platform</li>
<li>Java version: all version</li>
</ul>
<h3 dir="auto">Steps to reproduce this issue</h3>
<ol dir="auto">
<li>set SystemProperty "java.net.preferIPv6Addresses" to true.</li>
<li>call org.apache.dubbo.common.utils.NetUtils#isPreferIPV6Address().</li>
<li>check the return value.</li>
</ol>
<h3 dir="auto">Expected Result</h3>
<p dir="auto">org.apache.dubbo.common.utils.NetUtils#isPreferIPV6Address() will return true when SystemProperty "java.net.preferIPv6Addresses" set to true.</p>
<h3 dir="auto">Actual Result</h3>
<p dir="auto">org.apache.dubbo.common.utils.NetUtils#isPreferIPV6Address() method ignore SystemProperty "java.net.preferIPv6Addresses" and always return false</p>