sion-language/>expression</a>. Please note that if the datatype of a field is not istio.policy.v1beta1.Value,
then the expression&rsquo;s <a href=/v1.6/zh/docs/reference//config/policy-and-telemetry/expression-language/#type-checking>inferred type</a> must match the datatype of the field.</p><table class=message-fields><thead><tr><th>Field</th><th>Type</th><th>Description</th><th>Required</th></tr></thead><tbody><tr id=Template-trace_id><td><code>traceId</code></td><td><code>string</code></td><td><p>Trace I