[FLINK-30929] Add helpful message when ElasticsearchSink.Builder.build() throws an IllegalArgumentException.

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.13.6
• Component/s: Connectors / ElasticSearch
• Assignee: Unassigned
• Reporter: Kenny Wu
• Created: 06/Feb/23 13:00
• Updated: 07/Feb/23 08:22
• Resolved: 07/Feb/23 03:29

Description

When I test flink-connector-elasticsearch on my project. And I got an IllegalArgumentException with nothing helpful message. 

Here's the exception message: 

 

Exception in thread "main" java.lang.IllegalArgumentException
    at org.apache.flink.util.Preconditions.checkArgument(Preconditions.java:122)
    at org.apache.flink.streaming.connectors.elasticsearch7.Elasticsearch7ApiCallBridge.<init>(Elasticsearch7ApiCallBridge.java:61)
    at org.apache.flink.streaming.connectors.elasticsearch7.ElasticsearchSink.<init>(ElasticsearchSink.java:74)
    ... 

 

I could not see which exactly the argument was illegal.

After I read the code in (Elasticsearch7ApiCallBridge.java:61), I realized that proberbly  the ES hosts was empty. And finally fixed it.

I think helpful message should be printed when such an important argument is illegal and fails to build the connector.

And I'd love to improve it. thanks