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.
code Indicates the reason code for a configuration
field_name 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.