[BUG][kotlin-spring] missing JsonInclude import for optional+nullable-only models when using jsonNullable

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinSpringServerCodegen.java

@@ -1301,6 +1301,11 @@ public void postProcessModelProperty(CodegenModel model, CodegenProperty propert
         if (openApiNullable && !property.required && property.isNullable) {
             property.vendorExtensions.put("x-is-jackson-optional-nullable", true);
             model.imports.add("JsonNullable");
+            // The template always emits @field:JsonInclude(NON_ABSENT) for these fields,
+            // so the JsonInclude import must be present even when the model has no other
+            // property that would otherwise pull it in (e.g. a model with only
+            // optional+nullable fields).
+            model.imports.add("JsonInclude");
         }
 
         //Add imports for Jackson

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/SpringCodegen.java

@@ -1229,6 +1229,14 @@ public void postProcessModelProperty(CodegenModel model, CodegenProperty propert
         if (openApiNullable && !property.required && property.isNullable) {
             model.imports.add("JsonInclude");
         }
+        // Any nullable property is declared with the JsonNullable<T> type in the model template.
+        // Ensure the import is present whenever it is actually used, and only then. The template
+        // no longer emits an unconditional JsonNullable import, so model.imports is the single
+        // source of truth. AbstractJavaCodegen only adds it for optional+nullable; this also
+        // covers required+nullable.
+        if (openApiNullable && property.isNullable) {
+            model.imports.add("JsonNullable");
+        }
     }
 
     @Override

modules/openapi-generator/src/main/resources/JavaSpring/model.mustache

@@ -4,9 +4,6 @@ import java.net.URI;
 import java.util.Objects;
 {{#imports}}import {{import}};
 {{/imports}}
-{{#openApiNullable}}
-import org.openapitools.jackson.nullable.JsonNullable;
-{{/openApiNullable}}
 {{#serializableModel}}
 import java.io.Serializable;
 {{/serializableModel}}

modules/openapi-generator/src/test/java/org/openapitools/codegen/kotlin/spring/KotlinSpringServerCodegenTest.java

@@ -6714,6 +6714,28 @@ public void requiredNullable_scenario4_optionalNullable_hasNonAbsentAnnotation()
         assertFileContains(modelFile, "import com.fasterxml.jackson.annotation.JsonInclude");
     }
 
+    /**
+     * Regression test: a model whose ONLY property is optional + nullable
+     * (Scenario 4) with openApiNullable=true must still import
+     * {@code com.fasterxml.jackson.annotation.JsonInclude}. Previously the
+     * import was only added by a Scenario 3 (optional+non-nullable) property,
+     * so a model with only Scenario 4 fields emitted
+     * {@code @field:JsonInclude(NON_ABSENT)} without the corresponding import,
+     * producing uncompilable Kotlin.
+     */
+    @Test(description = "Scenario 4 – optional+nullable-only model must import JsonInclude")
+    public void requiredNullable_scenario4_optionalNullableOnly_importsJsonInclude() throws IOException {
+        Map<String, File> files = generateFromContract(
+                "src/test/resources/3_0/kotlin/optional-nullable-only.yaml",
+                Map.of(CodegenConstants.OPENAPI_NULLABLE, "true"));
+
+        Path modelFile = files.get("OptionalNullableOnlyModel.kt").toPath();
+        String content = Files.readString(modelFile);
+        Assert.assertTrue(content.contains("@field:JsonInclude(JsonInclude.Include.NON_ABSENT)"),
+                "optionalNullable must have @field:JsonInclude(NON_ABSENT)");
+        assertFileContains(modelFile, "import com.fasterxml.jackson.annotation.JsonInclude");
+    }
+
     /**
      * Without openApiNullable the optional+nullable field is a plain {@code Type?} — no
      * {@code @field:JsonInclude(NON_ABSENT)} should be emitted because {@code JsonNullable} is

modules/openapi-generator/src/test/resources/3_0/kotlin/optional-nullable-only.yaml

@@ -0,0 +1,29 @@
+openapi: 3.0.0
+info:
+  title: Optional Nullable Only Test
+  version: 1.0.0
+paths:
+  /test:
+    post:
+      operationId: testPost
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/OptionalNullableOnlyModel'
+      responses:
+        '200':
+          description: OK
+components:
+  schemas:
+    # Model whose only property is optional + nullable (Scenario 4). With
+    # openApiNullable=true it renders @field:JsonInclude(NON_ABSENT) and must
+    # therefore import com.fasterxml.jackson.annotation.JsonInclude even though
+    # no other property pulls that import in.
+    OptionalNullableOnlyModel:
+      type: object
+      properties:
+        optionalNullable:
+          type: string
+          format: uuid
+          nullable: true

modules/openapi-generator/src/test/resources/3_0/spring/petstore-sort-validation.yaml

@@ -686,6 +686,22 @@ paths:
         '400':
           description: Bad request
 
+  /nullable/optional-nullable-only:
+    post:
+      tags:
+        - nullable
+      summary: POST a model whose only property is optional+nullable — must compile (JsonInclude import)
+      operationId: postOptionalNullableOnly
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/OptionalNullableOnlyModel'
+      responses:
+        '200':
+          description: OK
+
 components:
   schemas:
     NullableModel:
@@ -710,6 +726,17 @@ components:
         optionalNullable:
           type: string
           nullable: true
+    # Regression guard: a model whose ONLY property is optional+nullable (Scenario 4).
+    # With openApiNullable=true it renders @field:JsonInclude(NON_ABSENT) and must import
+    # JsonInclude even though no other property pulls that import in. Without the import the
+    # generated sample fails to compile.
+    OptionalNullableOnlyModel:
+      type: object
+      properties:
+        optionalNullable:
+          type: string
+          format: uuid
+          nullable: true
     PetSort:
       type: string
       enum:

samples/client/petstore/spring-cloud-date-time/src/main/java/org/openapitools/model/Pet.java

@@ -12,7 +12,6 @@
 import java.time.OffsetDateTime;
 import org.springframework.format.annotation.DateTimeFormat;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-deprecated/src/main/java/org/openapitools/model/Category.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-deprecated/src/main/java/org/openapitools/model/ModelApiResponse.java

@@ -7,7 +7,6 @@
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-deprecated/src/main/java/org/openapitools/model/Order.java

@@ -9,7 +9,6 @@
 import java.time.OffsetDateTime;
 import org.springframework.format.annotation.DateTimeFormat;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-deprecated/src/main/java/org/openapitools/model/Pet.java

@@ -9,10 +9,10 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import org.openapitools.jackson.nullable.JsonNullable;
 import org.openapitools.model.Category;
 import org.openapitools.model.Tag;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-deprecated/src/main/java/org/openapitools/model/Tag.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-deprecated/src/main/java/org/openapitools/model/User.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-feign-without-url/src/main/java/org/openapitools/model/Category.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-feign-without-url/src/main/java/org/openapitools/model/ModelApiResponse.java

@@ -7,7 +7,6 @@
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-feign-without-url/src/main/java/org/openapitools/model/Order.java

@@ -9,7 +9,6 @@
 import java.time.OffsetDateTime;
 import org.springframework.format.annotation.DateTimeFormat;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-feign-without-url/src/main/java/org/openapitools/model/Pet.java

@@ -12,7 +12,6 @@
 import org.openapitools.model.Category;
 import org.openapitools.model.Tag;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-feign-without-url/src/main/java/org/openapitools/model/Tag.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-feign-without-url/src/main/java/org/openapitools/model/User.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-tags/src/main/java/org/openapitools/model/Category.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-tags/src/main/java/org/openapitools/model/ModelApiResponse.java

@@ -7,7 +7,6 @@
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-tags/src/main/java/org/openapitools/model/Order.java

@@ -9,7 +9,6 @@
 import java.time.OffsetDateTime;
 import org.springframework.format.annotation.DateTimeFormat;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-tags/src/main/java/org/openapitools/model/Pet.java

@@ -12,7 +12,6 @@
 import org.openapitools.model.Category;
 import org.openapitools.model.Tag;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-tags/src/main/java/org/openapitools/model/Tag.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud-tags/src/main/java/org/openapitools/model/User.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud/src/main/java/org/openapitools/model/Category.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud/src/main/java/org/openapitools/model/ModelApiResponse.java

@@ -7,7 +7,6 @@
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud/src/main/java/org/openapitools/model/Order.java

@@ -9,7 +9,6 @@
 import java.time.OffsetDateTime;
 import org.springframework.format.annotation.DateTimeFormat;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud/src/main/java/org/openapitools/model/Pet.java

@@ -12,7 +12,6 @@
 import org.openapitools.model.Category;
 import org.openapitools.model.Tag;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud/src/main/java/org/openapitools/model/Tag.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-cloud/src/main/java/org/openapitools/model/User.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-http-interface-bean-validation/src/main/java/org/openapitools/model/AdditionalPropertiesAnyTypeDto.java

@@ -7,7 +7,6 @@
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-http-interface-bean-validation/src/main/java/org/openapitools/model/AdditionalPropertiesArrayDto.java

@@ -8,7 +8,6 @@
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import java.util.List;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-http-interface-bean-validation/src/main/java/org/openapitools/model/AdditionalPropertiesBooleanDto.java

@@ -7,7 +7,6 @@
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-http-interface-bean-validation/src/main/java/org/openapitools/model/AdditionalPropertiesClassDto.java

@@ -14,7 +14,6 @@
 import org.openapitools.jackson.nullable.JsonNullable;
 import org.springframework.lang.Nullable;
 import java.util.NoSuchElementException;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-http-interface-bean-validation/src/main/java/org/openapitools/model/AdditionalPropertiesIntegerDto.java

@@ -7,7 +7,6 @@
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-http-interface-bean-validation/src/main/java/org/openapitools/model/AdditionalPropertiesNumberDto.java

@@ -8,7 +8,6 @@
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import java.math.BigDecimal;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;

samples/client/petstore/spring-http-interface-bean-validation/src/main/java/org/openapitools/model/AdditionalPropertiesObjectDto.java

@@ -8,7 +8,6 @@
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import java.util.Map;
 import org.springframework.lang.Nullable;
-import org.openapitools.jackson.nullable.JsonNullable;
 import java.time.OffsetDateTime;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.*;