How to iterate map if it is inside a object list in thyme leaf

public class additionalDate {
  @Field
  private String courier;
  @Field
  private Integer number;
  @Field
  private Date Date;
  @Field
  private Map<String, NameMap> mapName;
  @CreatedDate
  private Date created;
  @LastModifiedDate
  private Date lastModified;
}

how i can iterate map in thymeleaf i tried with below code but did't work.

[# th:each="mapName: ${additionalDate .mapName}"]
[(${mapName.key})]
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