Including a Java Object in the payload of a POST request to Camunda's '/rest/process-instance/count' endpoint to filter process instances

Question

For the POST endpoint ‘/rest/process-instance/count’ in Camunda, can I include a Java Object variable defined in my Java code within the payload?

For example, considering a payload structured as follows:

{"activityIdIn": \["Task1"\], "variables": \[{"name": "carColor", "operator": "eq", "value": "RED"}\]}

Where RED is an enum defined in my Java code. The objective is to retrieve all process instances in Task1 where carColor equals RED.