Hi Nic,

It would be good to get some clarity on those classes. Several methods from 
DataTypeUtils were used in Flink Connector Kafka and when I migrated the 
connector to Flink 2.1 [1] I had to deal with the fact that some of those 
methods had been removed [2] without first being deprecated.

That probably indicates that these classes aren't supposed to be public. But, 
as I said, it would be useful to clarify that. You should also look at how 
those classes evolve in Flink 2.x. 

Tom Cooper
@tomcooper.dev | https://tomcooper.dev

[1] https://github.com/apache/flink-connector-kafka/pull/187
[2] https://github.com/apache/flink/pull/26784

On Friday, 12 September 2025 at 15:17, Nic Townsend <[email protected]> 
wrote:

> Hi, there are two useful utilities classes:
> 
> -   
> https://nightlies.apache.org/flink/flink-docs-release-1.20/api/java//org/apache/flink/table/types/utils/DataTypeUtils.html
>     
> -   
> https://nightlies.apache.org/flink/flink-docs-release-1.20/api/java//org/apache/flink/table/types/logical/utils/LogicalTypeChecks.html
>     
> 
> 
> My use case is that I am converting from Table to DataStream and I have a 
> table that contains multiple time attributes (for e.g after a window join).
> 
> Unfortunately, the tables are generated from user input so I can't stop them 
> outputting multiple attributes. I need to programmatically strip the 
> attributes at the Java level - but these classes are marked as @internal.
> 
> Are they safe to use? Should I raise a PR to mark them as @PublicEvolving if 
> they are safe?
> 
> Many thanks
> 
> 
> -- 
> 
> Nic Townsend
> 
> IBM Event Processing
> 
> Architect / Senior Engineer
> 
> Slack: @nictownsend
> 
> Bluesky: @nict0wnsend.bsky.social
> 
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