Constraints validation failed in tosca-parser if the value passed as input parameter in tosca-template

[Niraj Singh]

While creating VNFD in tacker if any VDU property value in tosca-template is defined as input param and there is some constraints defined on it then tosca-parser failed at [1].

Example:

      Tosca-template
      ===============

     VDU1:
      type: tosca.nodes.nfv.VDU.Tacker
      properties:
        image: cirros-0.4.0-x86_64-disk
        flavor: { get_input: flavor }
        reservation_metadata:
          resource_type: { get_input: resource_type }
          id: { get_input: server_group_id }

 Constraints defined as below:

 /tacker_nfv_defs.yaml:
 ======================

  node_types:
    ...
    reservation_metadata:
   type: tosca.datatypes.tacker.VduReservationMetadata
   required: false

 /tacker_defs.yaml:
 ==================

  datatypes:
    ...
    tosca.datatypes.tacker.VduReservationMetadata:
     properties:
    resource_type:
      type: string
      required: true
      constraints:
     - valid_values: [ physical_host, virtual_instance ]
    id:
      type: string
      required: true

[1] https://github.com/openstack/tosca-parser/blob/master/toscaparser/elements/constraints.py#L186