{"namespace": "org.apache.flink.avro.generated",
 "type": "record",
 "name": "NasaMission",
 "fields": [
     {"name": "id", "type": "int"},
     {"name": "name", "type": "string"},
     {"name": "start_year",  "type": ["int", "null"]},
     {"name": "end_year", "type": ["int", "null"]}
 ]
}
