Designer can add custom properties by 'Add Property' in UI, however currently(el-alto) it does not have an functionality to set required from UI.

This story aims to support designer can set required param for each input which indicates an input is mandatory or optional.

In TOSCA template:

topology_template:
  inputs:
    param1:
      type: string
      description: my param
      required: true        # <== HERE

UI design proposal:
sdc_prop_required_rev4.pptx