【异常】Flink整合ES出错，The implementation of the provided ElasticsearchSinkFunction is not serializable.

一、异常内容

Exception in thread "main" java.lang.IllegalArgumentException: The implementation of the provided ElasticsearchSinkFunction is not serializable. The object probably contains or references non-serializable fields.
	at org.apache.flink.util.Preconditions.checkArgument(Preconditions.java:142)
	at org.apache.flink.streaming.connectors.elasticsearch.ElasticsearchSinkBase.<init>(ElasticsearchSinkBase.java:215)
	at org.apache.flink.streaming.connectors.elasticsearch7.ElasticsearchSink.<init>(Elasticsear
1
2
3