VulnerabilityAssessmentScanTriggerType type    
Defines values for VulnerabilityAssessmentScanTriggerType. 
KnownVulnerabilityAssessmentScanTriggerType can be used interchangeably with VulnerabilityAssessmentScanTriggerType,
this enum contains the known values that the service supports.
Known values supported by the service
OnDemand 
Recurring
type VulnerabilityAssessmentScanTriggerType = string