Specifies a comment that will be included in generated DDL.

By default, if on is not specified:

• when a field or property is annotated, the comment applies to the mapped column,
• when a collection is annotated, the comment applies to the collection table, and
• when an entity class is annotated, the comment applies to the primary table.

But when on is explicitly specified, the comment applies to the mapped table or column with the specified name.

For example:

@Entity
@Table(name = "book")
@SecondaryTable(name = "edition")
@Comment("The primary table for Book")
@Comment(on = "edition",
         value = "The secondary table for Book")
class Book { ... }