Simple entity

HelloEntity.java

@Data
// equals, hashcode, getters and setters
@Builder
// builder pattern
@NoArgsConstructor
// constructor
@AllArgsConstructor
// other constructor
@Entity
// persistence class declaration
@XmlRootElement
// xml marshalling
@EqualsAndHashCode(callSuper = true)
@ApiModel( value = "Hello Entity", description = "Hello resource representation" )
public class HelloEntity extends AbstractEntity implements Serializable /* in order to be sendable via JMS*/{
    /**
     * Serial
     */
    private static final transient long serialVersionUID = 6233801298404301547L;
    /**
     * Message
     */
    @XmlElement
    // XML node
    @NotNull(message = "message must not be null")
    // Validation for null object
    @Size(min = 2, max = 12, message = "message size must be between 2 and 12")
    // size validation
    @Pattern(regexp = "[a-zA-Z0-9]+", message = "must not contain special characters")
    // pattern validation
    @ApiModelProperty( value = "The thing to greet", required = true )
    private String helloMessage;
}