enum fails validation

[knap1930]

definitions:
  imageType:
    type: string
    enum:
      - "AVATAR"
      - "PROFILE"

fails validation with message

{
    "messages": 
    [
        "attribute definitions.imageType.properties is missing"
    ]
}

[knap1930]

I assume this is the root cause.. https://github.com/swagger-api/swagger-parser/pull/165