Nullable git tag messages

convention/src/main/kotlin/io/gitlab/jfronny/scripts/JGitExt.kt

@@ -33,7 +33,7 @@ fun Ref.resolveTag(repo: Repository): Tag = RevWalk(repo).use { walk ->
         // Lightweight (unannotated) tag
         // Copy information from commit
         val target = walk.parseCommit(objectId).resolve(repo)
-        return Tag(objectId, null, name, target, target.author, target.fullMessage, target.shortMessage, target.dateTime)
+        return Tag(objectId, null, name, target, target.author, null, null, target.dateTime)
     }
     walk.parseBody(rev)
     walk.parseBody(rev.`object`)
@@ -50,8 +50,8 @@ fun RevTag.resolve(commit: Commit): Tag {
         name,
         commit,
         Person(ident, ident.name, ident.emailAddress),
-        fullMessage,
-        shortMessage,
+        fullMessage.nullable,
+        shortMessage.nullable,
         ZonedDateTime.ofInstant(
             ident.`when`.toInstant(),
             ident.timeZone?.toZoneId() ?: ZoneOffset.UTC
@@ -79,6 +79,8 @@ fun RevCommit.resolve(repo: Repository): Commit = Commit(
     parents.map { ObjectId.toString(it) }
 )
 
+private val String?.nullable get() = if (this == null || this == "") null else this
+
 data class Tag(val id: ObjectId, val original: RevTag?, val fullName: String, val commit: Commit?, val tagger: Person?, val fullMessage: String?, val shortMessage: String?, val dateTime: ZonedDateTime?) {
     val name: String
         get() = Repository.shortenRefName(fullName)