VariableQueryParameterDto hast no property name. One cannot search for "identifier_eq_xy" as an example.
processVariables states:
"type": "array",
"items": {
"$ref": "#/components/schemas/VariableQueryParameterDto"
{color}},"description": "A JSON array to only include tasks that belong to a process instance with variables\nwith certain values. The array consists of JSON objects with three properties\n`name`, `operator` and `value`.