     public let draft: Bool
     public let prerelease: Bool
     public let createdAt: Date
-    public let publishedAt: Date
+    public let publishedAt: Date?
     public let author: User
 
     enum CodingKeys: String, CodingKey {

    }

    var encoding: HTTPEncoding {
        return .json
    }

    var params: [String: Any] {

    public let url: URL
    public let htmlURL: URL
    public let assetsURL: URL
    public let tarballURL: URL?
    public let zipballURL: URL?
    public let nodeId: String
    public let tagName: String
    public let commitish: String
