diff --git a/bin/configs/kotlin-jackson.yaml b/bin/configs/kotlin-jackson.yaml
index 2d37a29f38a..d16fee65eee 100644
--- a/bin/configs/kotlin-jackson.yaml
+++ b/bin/configs/kotlin-jackson.yaml
@@ -6,3 +6,4 @@ additionalProperties:
   serializationLibrary: jackson
   artifactId: kotlin-petstore-jackson
   enumPropertyNaming: UPPERCASE
+  enumUnknownDefaultCase: "true"
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/data_class.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/data_class.mustache
index c91f42078fa..c84e38b3f08 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/data_class.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/data_class.mustache
@@ -7,6 +7,9 @@ import com.squareup.moshi.Json
 import com.squareup.moshi.JsonClass
 {{/moshi}}
 {{#jackson}}
+{{#enumUnknownDefaultCase}}
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
+{{/enumUnknownDefaultCase}}
 import com.fasterxml.jackson.annotation.JsonProperty
 {{#discriminator}}
 import com.fasterxml.jackson.annotation.JsonSubTypes
@@ -114,7 +117,7 @@ import {{packageName}}.infrastructure.ITransformForStorage
         @SerializedName(value = {{#lambda.doublequote}}{{{value}}}{{/lambda.doublequote}}) {{&name}}({{{value}}}){{^-last}},{{/-last}}{{#-last}};{{/-last}}
         {{/gson}}
         {{#jackson}}
-        @JsonProperty(value = {{#lambda.doublequote}}{{{value}}}{{/lambda.doublequote}}) {{&name}}({{{value}}}){{^-last}},{{/-last}}{{#-last}};{{/-last}}
+        @JsonProperty(value = {{#lambda.doublequote}}{{{value}}}{{/lambda.doublequote}}) {{#enumUnknownDefaultCase}}{{#-last}}@JsonEnumDefaultValue {{/-last}}{{/enumUnknownDefaultCase}}{{&name}}({{{value}}}){{^-last}},{{/-last}}{{#-last}};{{/-last}}
         {{/jackson}}
         {{#kotlinx_serialization}}
         @SerialName(value = {{#lambda.doublequote}}{{{value}}}{{/lambda.doublequote}}) {{&name}}({{{value}}}){{^-last}},{{/-last}}{{#-last}};{{/-last}}
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache
index 8ff04b8ead1..24b95f65b32 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache
@@ -28,6 +28,9 @@ import kotlinx.datetime.Instant
 import java.util.UUID
 {{/gson}}
 {{#jackson}}
+{{#enumUnknownDefaultCase}}
+import com.fasterxml.jackson.databind.DeserializationFeature
+{{/enumUnknownDefaultCase}}
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.SerializationFeature
 import com.fasterxml.jackson.annotation.JsonInclude
@@ -104,6 +107,9 @@ import java.util.concurrent.atomic.AtomicLong
     val jacksonObjectMapper: ObjectMapper = jacksonObjectMapper()
         .findAndRegisterModules()
         .setSerializationInclusion(JsonInclude.Include.NON_ABSENT)
+        {{#enumUnknownDefaultCase}}
+        .configure(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE, true)
+        {{/enumUnknownDefaultCase}}
         .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false)
 {{/jackson}}
 {{#kotlinx_serialization}}
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 031dc852291..bcafbbef17c 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -193,7 +193,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
      enum class StatusFindPetsByStatus(val value: kotlin.String) {
          @JsonProperty(value = "available") AVAILABLE("available"),
          @JsonProperty(value = "pending") PENDING("pending"),
-         @JsonProperty(value = "sold") SOLD("sold")
+         @JsonProperty(value = "sold") SOLD("sold"),
      }
 
     /**
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
index ece5c413e12..6a09fd57f30 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -1,5 +1,6 @@
 package org.openapitools.client.infrastructure
 
+import com.fasterxml.jackson.databind.DeserializationFeature
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.SerializationFeature
 import com.fasterxml.jackson.annotation.JsonInclude
@@ -10,5 +11,6 @@ object Serializer {
     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)
 }
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt
index 71a7d74b06f..ff41aedca0b 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
index 5590e88cd83..2a59a8f3acd 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt
index ae6f6bc3b9f..5d72e185d7f 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -56,12 +57,13 @@ data class Order (
     /**
      * Order Status
      *
-     * Values: PLACED,APPROVED,DELIVERED
+     * Values: PLACED,APPROVED,DELIVERED,UNKNOWN_DEFAULT_OPEN_API
      */
     enum class Status(val value: kotlin.String) {
         @JsonProperty(value = "placed") PLACED("placed"),
         @JsonProperty(value = "approved") APPROVED("approved"),
-        @JsonProperty(value = "delivered") DELIVERED("delivered");
+        @JsonProperty(value = "delivered") DELIVERED("delivered"),
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue UNKNOWN_DEFAULT_OPEN_API("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt
index ea5a3dce8c4..c9863eb6c32 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt
@@ -18,6 +18,7 @@ package org.openapitools.client.models
 import org.openapitools.client.models.Category
 import org.openapitools.client.models.Tag
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -58,12 +59,13 @@ data class Pet (
     /**
      * pet status in the store
      *
-     * Values: AVAILABLE,PENDING,SOLD
+     * Values: AVAILABLE,PENDING,SOLD,UNKNOWN_DEFAULT_OPEN_API
      */
     enum class Status(val value: kotlin.String) {
         @JsonProperty(value = "available") AVAILABLE("available"),
         @JsonProperty(value = "pending") PENDING("pending"),
-        @JsonProperty(value = "sold") SOLD("sold");
+        @JsonProperty(value = "sold") SOLD("sold"),
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue UNKNOWN_DEFAULT_OPEN_API("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt
index f5f600cc374..bfff056241c 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/User.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/User.kt
index 7872ed7da4d..48cabe85898 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/User.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/models/User.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
index ece5c413e12..6a09fd57f30 100644
--- a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+++ b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -1,5 +1,6 @@
 package org.openapitools.client.infrastructure
 
+import com.fasterxml.jackson.databind.DeserializationFeature
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.SerializationFeature
 import com.fasterxml.jackson.annotation.JsonInclude
@@ -10,5 +11,6 @@ object Serializer {
     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)
 }
diff --git a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt
index 71a7d74b06f..ff41aedca0b 100644
--- a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt
+++ b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
index 5590e88cd83..2a59a8f3acd 100644
--- a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
+++ b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt
index bfedd1b5284..01008523bcb 100644
--- a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt
+++ b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -62,7 +63,7 @@ data class Order (
         @JsonProperty(value = "placed") placed("placed"),
         @JsonProperty(value = "approved") approved("approved"),
         @JsonProperty(value = "delivered") delivered("delivered"),
-        @JsonProperty(value = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt
index 1da246bb31d..17abefb22ca 100644
--- a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt
+++ b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt
@@ -18,6 +18,7 @@ package org.openapitools.client.models
 import org.openapitools.client.models.Category
 import org.openapitools.client.models.Tag
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -65,7 +66,7 @@ data class Pet (
         @JsonProperty(value = "available") available("available"),
         @JsonProperty(value = "pending") pending("pending"),
         @JsonProperty(value = "sold") sold("sold"),
-        @JsonProperty(value = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt
index f5f600cc374..bfff056241c 100644
--- a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt
+++ b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/User.kt b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/User.kt
index 7872ed7da4d..48cabe85898 100644
--- a/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/User.kt
+++ b/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/models/User.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt
index 71a7d74b06f..ff41aedca0b 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Category.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
index 5590e88cd83..2a59a8f3acd 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt
index bfedd1b5284..01008523bcb 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Order.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -62,7 +63,7 @@ data class Order (
         @JsonProperty(value = "placed") placed("placed"),
         @JsonProperty(value = "approved") approved("approved"),
         @JsonProperty(value = "delivered") delivered("delivered"),
-        @JsonProperty(value = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt
index ba5fd69df76..aa4e724e0e6 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Pet.kt
@@ -18,6 +18,7 @@ package org.openapitools.client.models
 import org.openapitools.client.models.Category
 import org.openapitools.client.models.Tag
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -64,7 +65,7 @@ data class Pet (
         @JsonProperty(value = "available") available("available"),
         @JsonProperty(value = "pending") pending("pending"),
         @JsonProperty(value = "sold") sold("sold"),
-        @JsonProperty(value = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt
index f5f600cc374..bfff056241c 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/Tag.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/User.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/User.kt
index 7872ed7da4d..48cabe85898 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/User.kt
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/models/User.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
index ece5c413e12..6a09fd57f30 100644
--- a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -1,5 +1,6 @@
 package org.openapitools.client.infrastructure
 
+import com.fasterxml.jackson.databind.DeserializationFeature
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.SerializationFeature
 import com.fasterxml.jackson.annotation.JsonInclude
@@ -10,5 +11,6 @@ object Serializer {
     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)
 }
diff --git a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Category.kt b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Category.kt
index 71a7d74b06f..ff41aedca0b 100644
--- a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Category.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Category.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
index 5590e88cd83..2a59a8f3acd 100644
--- a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Order.kt b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Order.kt
index bfedd1b5284..01008523bcb 100644
--- a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Order.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Order.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -62,7 +63,7 @@ data class Order (
         @JsonProperty(value = "placed") placed("placed"),
         @JsonProperty(value = "approved") approved("approved"),
         @JsonProperty(value = "delivered") delivered("delivered"),
-        @JsonProperty(value = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Pet.kt b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Pet.kt
index 1da246bb31d..17abefb22ca 100644
--- a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Pet.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Pet.kt
@@ -18,6 +18,7 @@ package org.openapitools.client.models
 import org.openapitools.client.models.Category
 import org.openapitools.client.models.Tag
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -65,7 +66,7 @@ data class Pet (
         @JsonProperty(value = "available") available("available"),
         @JsonProperty(value = "pending") pending("pending"),
         @JsonProperty(value = "sold") sold("sold"),
-        @JsonProperty(value = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Tag.kt b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Tag.kt
index f5f600cc374..bfff056241c 100644
--- a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Tag.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/Tag.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/User.kt b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/User.kt
index 7872ed7da4d..48cabe85898 100644
--- a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/User.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/models/User.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
index ece5c413e12..6a09fd57f30 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -1,5 +1,6 @@
 package org.openapitools.client.infrastructure
 
+import com.fasterxml.jackson.databind.DeserializationFeature
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.SerializationFeature
 import com.fasterxml.jackson.annotation.JsonInclude
@@ -10,5 +11,6 @@ object Serializer {
     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)
 }
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Category.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Category.kt
index 71a7d74b06f..ff41aedca0b 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Category.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Category.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
index 5590e88cd83..2a59a8f3acd 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Order.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Order.kt
index bfedd1b5284..01008523bcb 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Order.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Order.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -62,7 +63,7 @@ data class Order (
         @JsonProperty(value = "placed") placed("placed"),
         @JsonProperty(value = "approved") approved("approved"),
         @JsonProperty(value = "delivered") delivered("delivered"),
-        @JsonProperty(value = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Pet.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Pet.kt
index 1da246bb31d..17abefb22ca 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Pet.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Pet.kt
@@ -18,6 +18,7 @@ package org.openapitools.client.models
 import org.openapitools.client.models.Category
 import org.openapitools.client.models.Tag
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -65,7 +66,7 @@ data class Pet (
         @JsonProperty(value = "available") available("available"),
         @JsonProperty(value = "pending") pending("pending"),
         @JsonProperty(value = "sold") sold("sold"),
-        @JsonProperty(value = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Tag.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Tag.kt
index f5f600cc374..bfff056241c 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Tag.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/Tag.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/User.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/User.kt
index 7872ed7da4d..48cabe85898 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/User.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/models/User.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
index ece5c413e12..6a09fd57f30 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -1,5 +1,6 @@
 package org.openapitools.client.infrastructure
 
+import com.fasterxml.jackson.databind.DeserializationFeature
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.SerializationFeature
 import com.fasterxml.jackson.annotation.JsonInclude
@@ -10,5 +11,6 @@ object Serializer {
     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)
 }
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Category.kt b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Category.kt
index 71a7d74b06f..ff41aedca0b 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Category.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Category.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
index 5590e88cd83..2a59a8f3acd 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Order.kt b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Order.kt
index bfedd1b5284..01008523bcb 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Order.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Order.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -62,7 +63,7 @@ data class Order (
         @JsonProperty(value = "placed") placed("placed"),
         @JsonProperty(value = "approved") approved("approved"),
         @JsonProperty(value = "delivered") delivered("delivered"),
-        @JsonProperty(value = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Pet.kt b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Pet.kt
index 1da246bb31d..17abefb22ca 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Pet.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Pet.kt
@@ -18,6 +18,7 @@ package org.openapitools.client.models
 import org.openapitools.client.models.Category
 import org.openapitools.client.models.Tag
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
@@ -65,7 +66,7 @@ data class Pet (
         @JsonProperty(value = "available") available("available"),
         @JsonProperty(value = "pending") pending("pending"),
         @JsonProperty(value = "sold") sold("sold"),
-        @JsonProperty(value = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
+        @JsonProperty(value = "unknown_default_open_api") @JsonEnumDefaultValue unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Tag.kt b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Tag.kt
index f5f600cc374..bfff056241c 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Tag.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/Tag.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/User.kt b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/User.kt
index 7872ed7da4d..48cabe85898 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/User.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/models/User.kt
@@ -16,6 +16,7 @@
 package org.openapitools.client.models
 
 
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue
 import com.fasterxml.jackson.annotation.JsonProperty
 
 /**