fix(kotlin-client): handle Jackson 3 API changes in Serializer template

Jackson 3 moved/renamed several APIs:
- findAndRegisterModules() not needed (modules auto-discovered)
- SerializationFeature.WRITE_DATES_AS_TIMESTAMPS -> DateTimeFeature
- DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE -> EnumFeature

Add conditionals in Serializer.kt.mustache for Jackson 2 vs 3.

Author: yonatankarp

modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache

@@ -32,7 +32,15 @@ import java.util.UUID
 {{#jackson}}
 import {{jacksonPackage}}.databind.DeserializationFeature
 import {{jacksonPackage}}.databind.ObjectMapper
+{{^useJackson3}}
 import {{jacksonPackage}}.databind.SerializationFeature
+{{/useJackson3}}
+{{#useJackson3}}
+import {{jacksonPackage}}.databind.cfg.DateTimeFeature
+{{#enumUnknownDefaultCase}}
+import {{jacksonPackage}}.databind.cfg.EnumFeature
+{{/enumUnknownDefaultCase}}
+{{/useJackson3}}
 import com.fasterxml.jackson.annotation.JsonInclude
 import {{jacksonPackage}}.module.kotlin.jacksonObjectMapper
 {{/jackson}}
@@ -122,12 +130,24 @@ import java.util.concurrent.atomic.AtomicLong
 {{#jackson}}
     @JvmStatic
     val jacksonObjectMapper: ObjectMapper = jacksonObjectMapper()
+        {{^useJackson3}}
         .findAndRegisterModules()
+        {{/useJackson3}}
         .setSerializationInclusion(JsonInclude.Include.NON_ABSENT)
         {{#enumUnknownDefaultCase}}
+        {{#useJackson3}}
+        .configure(EnumFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE, true)
+        {{/useJackson3}}
+        {{^useJackson3}}
         .configure(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE, true)
+        {{/useJackson3}}
         {{/enumUnknownDefaultCase}}
+        {{#useJackson3}}
+        .configure(DateTimeFeature.WRITE_DATES_AS_TIMESTAMPS, false)
+        {{/useJackson3}}
+        {{^useJackson3}}
         .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false)
+        {{/useJackson3}}
         .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, {{failOnUnknownProperties}})
 {{/jackson}}
 {{#kotlinx_serialization}}

samples/client/petstore/kotlin-jackson3/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt

@@ -2,16 +2,16 @@ package org.openapitools.client.infrastructure
 
 import tools.jackson.databind.DeserializationFeature
 import tools.jackson.databind.ObjectMapper
-import tools.jackson.databind.SerializationFeature
+import tools.jackson.databind.cfg.DateTimeFeature
+import tools.jackson.databind.cfg.EnumFeature
 import com.fasterxml.jackson.annotation.JsonInclude
 import tools.jackson.module.kotlin.jacksonObjectMapper
 
 object Serializer {
     @JvmStatic
     val jacksonObjectMapper: ObjectMapper = jacksonObjectMapper()
-        .findAndRegisterModules()
         .setSerializationInclusion(JsonInclude.Include.NON_ABSENT)
-        .configure(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE, true)
-        .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false)
+        .configure(EnumFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE, true)
+        .configure(DateTimeFeature.WRITE_DATES_AS_TIMESTAMPS, false)
         .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
 }