scala> schemaTyped("a").getComment
res0: Option[String] = None
scala> schemaTyped("a").withComment("this is a comment").getComment
res1: Option[String] = Some(this is a comment)StructField
A StructField describes a single field in a StructType. It has a name, the type and whether or not it be empty, and an optional metadata and a comment.
A comment is a part of metadata under comment key and is used to build a Hive column or when describing a table.