问题 I'm using Flink to process the data coming from some data source (such as Kafka, Pravega etc). In my case, the data source is Pravega, which provided me a flink connector. My data source is sending me some JSON data as below: {"device":"rand-numeric","id":"b4728895-741f-466a-b87b-79c7590893b4","origin":"1591095418904441036","readings":[{"origin":"1591095418904328442","valueType":"Int64","name":"int","device":"rand-numeric","value":"0"}]} Here is my piece of code: import org.apache.flink