e class=language-yaml data-expandlinks=true data-repo=istio>source_principal: source.principal | &#34;unknown&#34;
</code></pre></li><li><p><strong>Source App</strong>: This identifies the source app based on <code>app</code> label of the
source workload.</p><pre><code class=language-yaml data-expandlinks=true data-repo=istio>source_app: source.labels[&#34;app&#34;] | &#34;unknown&#34;
</code></pre></li><li><p><strong>Source Version</strong>: This identifies the version of the source workload.</p><pre><code