a.api.streams"><code>ApplicationId</code></a> instance if the environment is already started,
                      otherwise <code>null</code>.</dd>
</dl>
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<h4>topologyProviders</h4>
<pre class="methodSignature"><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Set.html?is-external=true" title="class or interface in java.util" class="externalLink">Set</a>&lt;<a href="providers