Translation of an interface-less node results in a HOT resource with "type: null"

[Vahid Hashemian]

When a node like (as currently exists in tosca_elk.yaml)

    mongo_db:
      type: tosca.nodes.Database
      requirements:
        - host:
            node: mongo_dbms

that does not have any interfaces is translated into HOT it results in a resource like this

  mongo_db:
    type: null
    depends_on:
      - mongo_dbms_start_deploy

which is not a valid HOT resource due to "type: null".

A mechanism should be in place in situations like this so the mongo_db resource is bypassed in the HOT output, but at the same time the implied dependencies are preserved.

[Sahdev Zala (spzala)]

I believe the example is not valid anymore but we should provide fix for any similar cases.