title: Azure Bicep: setting a null value if the property doesn't exist
body: <p>I am deploying schedules for the azure update management service through bicep. My code is as below:</p>
  <pre><code>param parSchedules array = [
    {
      name: 'mysched1'
      monthlyOccurrencesDay: null
      monthlyOccurrencesOccurence: null
      DaysOfWeek: 'Wednesday'
      StartTime: '${parBaseTimeForUpdateSchedules}T19:00:00'
      tag: {
        Update: [
          'tag1'
        ]
      }
    }
    {
      name: 'mysched2'
      monthlyOccurrencesDay: 'Wednesday'
      monthlyOccurrencesOccurence: 1
      DaysOfWeek: 'Wednesday'
      StartTime: '${parBaseTimeForUpdateSchedules}T07:00:00'
      tag: {
        Update: [
          'tag2'
        ]
      }
    }
  ]
  
  
  resource resUpdateschedule 'Microsoft.Automation/automationAccounts/softwareUpdateConfigurations@2019-06-01' = [for schedule in parSchedules: {
    name: schedule.name
    parent: resAutomationAccount
    properties: {
      scheduleInfo: {
        advancedSchedule: {
          monthlyOccurrences: [
            {
              day: schedule.monthlyOccurrencesDay
              occurrence: schedule.monthlyOccurrencesOccurence
            }
          ]
          weekDays: [
            schedule.DaysOfWeek
          ]
        }
        description: ''
        frequency: 'Week'
        interval: 1
        isEnabled: true
        startTime: schedule.StartTime
        timeZone: 'UTC'
      }
      updateConfiguration: {
        duration: 'PT2H'
        operatingSystem: 'Windows'
        targets: {
          azureQueries: [
            {
              locations: [
                parLocation
              ]
              scope: [
                subscription().id
              ]
              tagSettings: {
                tags: schedule.tag
              }
            }
          ]
        }
        windows: {
          includedUpdateClassifications: 'Critical, Security'
          rebootSetting: 'IfRequired'
        }
      }
    }
  }]
  </code></pre>
  <p>I am getting error with this because null value is not accepted for <strong>monthlyOccurrencesDay</strong> and monthlyOccurrencesOccurence. So what I want is to be able to use the same list containing different types of schedules (with and without <strong>monthlyOccurrencesOccurence</strong>) by looping the same resource. Like <strong>if the values of monthlyOccurrencesOccurence is null, it shouldn't take into consideration this property.</strong> Is that possible at all?</p>