Defines a custom error message used by CreateScanConfig
and UpdateScanConfig APIs when scan configuration validation fails. It
is also reported as part of a ScanRunErrorTrace message if scan
validation fails due to a scan configuration error.
Indicates the full name of the ScanConfig field that triggers
this error, for example "scan_config.max_qps". This field is
provided for troubleshooting purposes only and its actual
value can change in the future.