Classes in the Java API Client contain two kinds of methods and properties:
Methods and properties that are part of the API, such as
SearchResponse.maxScore(). They are derived from their respective names in the Elasticsearch JSON API using the standard Java
Methods and properties that are part of the framework on which the Java API
Client is built, such as
Query._kind(). These methods and properties are prefixed with an underscore to both avoid any naming conflicts with API names, and as an easy way to distinguish the API from the framework.
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