What does the "org.hibernate.InstantiationException" error message mean when it says "No default constructor for entity: principal.Cliente"?

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The "org.hibernate.InstantiationException" error message means that Hibernate is unable to create an instance of the class "principal.Cliente". The reason for this error message is that Hibernate is expecting there to be a default constructor (a constructor with no arguments) for the "principal.Cliente" class, but one is not present. Hibernate requires a default constructor to be present in order to create instances of the entity class.