add missing JsonClassDiscriminator import

Author: yshrsmz

modules/openapi-generator/src/main/resources/kotlin-client/data_class.mustache

@@ -54,6 +54,9 @@ import kotlinx.parcelize.Parcelize
 import kotlinx.serialization.*
 import kotlinx.serialization.descriptors.*
 import kotlinx.serialization.encoding.*
+{{#discriminator}}
+import kotlinx.serialization.json.JsonClassDiscriminator
+{{/discriminator}}
 {{/multiplatform}}
 {{#serializableModel}}
 import java.io.Serializable

samples/client/petstore/kotlin-multiplatform-allOff-discriminator/.openapi-generator/FILES

@@ -1,4 +1,3 @@
-.openapi-generator-ignore
 README.md
 build.gradle.kts
 docs/Animal.md
@@ -26,6 +25,3 @@ src/commonMain/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
 src/commonMain/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
 src/commonMain/kotlin/org/openapitools/client/models/Animal.kt
 src/commonMain/kotlin/org/openapitools/client/models/Bird.kt
-src/test/kotlin/org/openapitools/client/apis/BirdApiTest.kt
-src/test/kotlin/org/openapitools/client/models/AnimalTest.kt
-src/test/kotlin/org/openapitools/client/models/BirdTest.kt

samples/client/petstore/kotlin-multiplatform-allOff-discriminator/src/commonMain/kotlin/org/openapitools/client/models/Animal.kt

@@ -19,6 +19,7 @@ package org.openapitools.client.models
 import kotlinx.serialization.*
 import kotlinx.serialization.descriptors.*
 import kotlinx.serialization.encoding.*
+import kotlinx.serialization.json.JsonClassDiscriminator
 
 /**
  *