# Meaning of packages with underscore in elastic-search Java language-client

**URL:** <https://discuss.elastic.co/t/meaning-of-packages-with-underscore-in-elastic-search-java-language-client/371317>\
**Category:** Elasticsearch\
**Tags:** language-clients\
**Created:** [December 2, 2024, 1:51pm UTC](https://discuss.elastic.co/t/meaning-of-packages-with-underscore-in-elastic-search-java-language-client/371317 "2024-12-02T13:51:46Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Hans\_Kruse](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hans_kruse/32/54739_2.png) [@Hans\_Kruse](https://discuss.elastic.co/u/Hans_Kruse)\
**Post date:** [December 2, 2024, 1:51pm UTC](https://discuss.elastic.co/t/meaning-of-packages-with-underscore-in-elastic-search-java-language-client/371317/1 "2024-12-02T13:51:46Z")

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What is the meaning of the underscore in the package names of the elasticsearch-java language-client?

We are migrating software that uses the Highlevel and low-level 7.x.y SDK's to the newer elasticsearch-java 8.x.y SDK.

At Elasticon Amsterdam I had a nice chat with David Pilato. He confirmed me that the way we approached the migration was right. Merci beaucoup David.

David suggested to ask in this discuss what the meaning of the `_` is. More specifically everything under the package _co.elastic.clients.elasticsearch.\_types_

Is it somewhat private or not stable when upgrading a newer version?

See David Pilato's blog post for the core issues with converting:  
[Switching from the Java High Level Rest Client to the new Java API Client | Elastic Blog](https://www.elastic.co/blog/switching-from-the-java-high-level-rest-client-to-the-new-java-api-client)

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**Author:** ![ltrotta](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/ltrotta/32/124003_2.png) [@ltrotta](https://discuss.elastic.co/u/ltrotta)\
**Post date:** [December 2, 2024, 1:59pm UTC](https://discuss.elastic.co/t/meaning-of-packages-with-underscore-in-elastic-search-java-language-client/371317/2 "2024-12-02T13:59:34Z")

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Hello!  
We use underscores in the java client to easily tell apart Elasticsearch API methods from utility library methods. So for example `search` will call the matching Elasticsearch API, while `_jsonpMapper()` will call the utility method to return the configured JsonMapper. So no risk in using them at all!

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**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\
**Post date:** [December 2, 2024, 2:26pm UTC](https://discuss.elastic.co/t/meaning-of-packages-with-underscore-in-elastic-search-java-language-client/371317/3 "2024-12-02T14:26:19Z")

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And thank you for helping me fixing my demo project with much more appropriate java code 😉

I still need to push the code 😃