[BUG][Kotlin] Add default values to optional parameters for jvm-spring-webclient and jvm-spring-restclient#17393

wing328 merged 3 commits intoOpenAPITools:masterOpenAPITools/openapi-generator:masterfrom

MatthiasGabriel:fix/kotlin-jvm-spring-webclient-optional-paramsMatthiasGabriel/openapi-generator:fix/kotlin-jvm-spring-webclient-optional-paramsCopy head branch name to clipboard