only consider requests for a certain destination service when troubleshooting application behavior.</p><p>The configuration instructs Mixer to populate values for these dimensions based on attribute values and literal values. For instance, for the <code>source</code> dimension, the new config requests that the value be taken from the <code>source.service</code> attribute. If that attribute value is not populated, the rule instructs Mixer to use a default value of <code>"unknown"</code>. For the <code>messag