[Spark] List<String> Encoders

/**
 * Converts a set of FHIR resources to JSON.
 *
 * @param dataset a dataset containing FHIR resources
 * @param resourceType the FHIR resource type
 * @return a dataset of JSON strings for the FHIR resources
 */
public static Dataset<String> toJson(Dataset<?> dataset, String resourceType) {

  Dataset<IBaseResource> resourceDataset =
      dataset.as(FhirEncoders.forStu3()
          .getOrCreate()
          .of(resourceType));

  return resourceDataset.map(new ToJson(), Encoders.STRING());
}

[출처] https://www.programcreek.com/java-api-examples/index.php?api=org.apache.spark.sql.Encoders