languageVersion

Target language version for the generated code.

Only valid when generateKotlinModels is true.

Must be either "1.4" or "1.5".

Note: "1.4", while still supported, is not useful since Apollo Kotlin requires Kotlin 1.5+. It is considered deprecated.

Using an higher languageVersion allows generated code to use more language features like sealed interfaces in Kotlin 1.5 for an example.

See also https://kotlinlang.org/docs/gradle.html#attributes-common-to-jvm-and-js

Default: use the version of the Kotlin plugin.