public static void toJSON(OutputWriter jsonOutputWriter, Modification model, Material material) { jsonOutputWriter .addLinks(linksWriter -> { linksWriter.addLink("vsm", Routes.Materials.vsm(material.getFingerprint(), model.getRevision())); }) .addIfNotNull("user_name", model.getUserName()) .addIfNotNull("email_address", model.getEmailAddress()) .addIfNotNull("revision", model.getRevision()) .addIfNotNull("modified_time", model.getModifiedTime()) .addIfNotNull("comment", model.getComment()); } }