4.1.0

• Support custom serialization of parameters in GraphQLOperationRequest #464 #472 #473
• Support interfaces to extend other interfaces (graphql/graphql-spec#373) #468 #469
• Support message for @deprecated directive #445 #471

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• Kotlin support (via generatedLanguage = KOTLIN)
• Scala support (via generatedLanguage = SCALA)

Kudos to @jxnu-liguobin for Kotlin and Scala support!