[java][feign] Fix model combining properties and additional properties (#19713)

bin/utils/test_file_list.yaml

@@ -53,6 +53,8 @@
   sha256: 15eeb6d8a9a79d0f1930b861540d9c5780d6c49ea4fdb68269ac3e7ec481e142
 - filename: "samples/client/petstore/java/webclient/src/test/java/org/openapitools/client/JacksonTest.java"
   sha256: 45cdaba3d2adc212cd4f0184ad475419a95e2326254c2ef84175e210c922b2f3
+- filename: "samples/client/petstore/java/feign/src/test/java/org/openapitools/client/JacksonTest.java"
+  sha256: 45cdaba3d2adc212cd4f0184ad475419a95e2326254c2ef84175e210c922b2f3
 # rust axum test files
 - filename: "samples/server/petstore/rust-axum/output/rust-axum-oneof/tests/oneof_with_discriminator.rs"
   sha256: 2d4f5a069fdcb3057bb078d5e75b3de63cd477b97725e457079df24bd2c30600

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

@@ -506,6 +506,14 @@ public class JavaClientCodegen extends AbstractJavaCodegen
                 supportingFiles.add(new SupportingFile("ParamExpander.mustache", invokerFolder, "ParamExpander.java"));
             }
             supportingFiles.add(new SupportingFile("EncodingUtils.mustache", invokerFolder, "EncodingUtils.java"));
+
+            // Composed schemas can have the 'additionalProperties' keyword, as specified in JSON schema.
+            // In principle, this should be enabled by default for all code generators. However due to limitations
+            // in other code generators, support needs to be enabled on a case-by-case basis.
+            // The flag below should be set for all Java libraries, but the templates need to be ported
+            // one by one for each library.
+            supportsAdditionalPropertiesWithComposedSchema = true;
+
         } else if (OKHTTP_GSON.equals(getLibrary()) || StringUtils.isEmpty(getLibrary())) {
             // the "okhttp-gson" library template requires "ApiCallback.mustache" for async call
             supportingFiles.add(new SupportingFile("ApiCallback.mustache", invokerFolder, "ApiCallback.java"));

modules/openapi-generator/src/main/resources/Java/libraries/feign/pojo.mustache

@@ -263,7 +263,8 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
     }{{#hasVars}}
     {{classname}} {{classVarName}} = ({{classname}}) o;
     return {{#vars}}{{#vendorExtensions.x-is-jackson-optional-nullable}}equalsNullable(this.{{name}}, {{classVarName}}.{{name}}){{/vendorExtensions.x-is-jackson-optional-nullable}}{{^vendorExtensions.x-is-jackson-optional-nullable}}{{#isByteArray}}Arrays{{/isByteArray}}{{^isByteArray}}Objects{{/isByteArray}}.equals(this.{{name}}, {{classVarName}}.{{name}}){{/vendorExtensions.x-is-jackson-optional-nullable}}{{^-last}} &&
-        {{/-last}}{{/vars}}{{#parent}} &&
+        {{/-last}}{{/vars}}{{#additionalPropertiesType}} &&
+        Objects.equals(this.additionalProperties, {{classVarName}}.additionalProperties){{/additionalPropertiesType}}{{#parent}} &&
         super.equals(o){{/parent}};{{/hasVars}}{{^hasVars}}
     return {{#parent}}super.equals(o){{/parent}}{{^parent}}true{{/parent}};{{/hasVars}}
   {{/useReflectionEqualsHashCode}}
@@ -279,7 +280,7 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
     return HashCodeBuilder.reflectionHashCode(this);
   {{/useReflectionEqualsHashCode}}
   {{^useReflectionEqualsHashCode}}
-    return Objects.hash({{#vars}}{{#vendorExtensions.x-is-jackson-optional-nullable}}hashCodeNullable({{name}}){{/vendorExtensions.x-is-jackson-optional-nullable}}{{^vendorExtensions.x-is-jackson-optional-nullable}}{{^isByteArray}}{{name}}{{/isByteArray}}{{#isByteArray}}Arrays.hashCode({{name}}){{/isByteArray}}{{/vendorExtensions.x-is-jackson-optional-nullable}}{{^-last}}, {{/-last}}{{/vars}}{{#parent}}{{#hasVars}}, {{/hasVars}}super.hashCode(){{/parent}});
+    return Objects.hash({{#vars}}{{#vendorExtensions.x-is-jackson-optional-nullable}}hashCodeNullable({{name}}){{/vendorExtensions.x-is-jackson-optional-nullable}}{{^vendorExtensions.x-is-jackson-optional-nullable}}{{^isByteArray}}{{name}}{{/isByteArray}}{{#isByteArray}}Arrays.hashCode({{name}}){{/isByteArray}}{{/vendorExtensions.x-is-jackson-optional-nullable}}{{^-last}}, {{/-last}}{{/vars}}{{#parent}}{{#hasVars}}, {{/hasVars}}super.hashCode(){{/parent}}{{#additionalPropertiesType}}, additionalProperties{{/additionalPropertiesType}});
   {{/useReflectionEqualsHashCode}}
   }{{#vendorExtensions.x-jackson-optional-nullable-helpers}}
 
@@ -300,6 +301,9 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
     {{#vars}}
     sb.append("    {{name}}: ").append({{#isPassword}}"*"{{/isPassword}}{{^isPassword}}toIndentedString({{name}}){{/isPassword}}).append("\n");
     {{/vars}}
+    {{#additionalPropertiesType}}
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
+    {{/additionalPropertiesType}}
     sb.append("}");
     return sb.toString();
   }

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/model/AdditionalPropertiesAnyType.java

@@ -28,8 +28,6 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.fasterxml.jackson.annotation.JsonValue;
 import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
-import java.util.HashMap;
-import java.util.Map;
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 
@@ -41,13 +39,12 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 })
 @javax.annotation.concurrent.Immutable
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.12.0-SNAPSHOT")
-public class AdditionalPropertiesAnyType extends HashMap<String, Object> {
+public class AdditionalPropertiesAnyType {
   public static final String JSON_PROPERTY_NAME = "name";
   @javax.annotation.Nullable
   private String name;
 
   public AdditionalPropertiesAnyType() {
-
   }
 
   public AdditionalPropertiesAnyType name(@javax.annotation.Nullable String name) {
@@ -134,8 +131,8 @@ public class AdditionalPropertiesAnyType extends HashMap<String, Object> {
   public String toString() {
     StringBuilder sb = new StringBuilder();
     sb.append("class AdditionalPropertiesAnyType {\n");
-    sb.append("    ").append(toIndentedString(super.toString())).append("\n");
     sb.append("    name: ").append(toIndentedString(name)).append("\n");
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
     sb.append("}");
     return sb.toString();
   }

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/model/AdditionalPropertiesArray.java

@@ -28,9 +28,7 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.fasterxml.jackson.annotation.JsonValue;
 import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 
@@ -42,13 +40,12 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 })
 @javax.annotation.concurrent.Immutable
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.12.0-SNAPSHOT")
-public class AdditionalPropertiesArray extends HashMap<String, List> {
+public class AdditionalPropertiesArray {
   public static final String JSON_PROPERTY_NAME = "name";
   @javax.annotation.Nullable
   private String name;
 
   public AdditionalPropertiesArray() {
-
   }
 
   public AdditionalPropertiesArray name(@javax.annotation.Nullable String name) {
@@ -135,8 +132,8 @@ public class AdditionalPropertiesArray extends HashMap<String, List> {
   public String toString() {
     StringBuilder sb = new StringBuilder();
     sb.append("class AdditionalPropertiesArray {\n");
-    sb.append("    ").append(toIndentedString(super.toString())).append("\n");
     sb.append("    name: ").append(toIndentedString(name)).append("\n");
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
     sb.append("}");
     return sb.toString();
   }

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/model/AdditionalPropertiesBoolean.java

@@ -28,8 +28,6 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.fasterxml.jackson.annotation.JsonValue;
 import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
-import java.util.HashMap;
-import java.util.Map;
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 
@@ -41,13 +39,12 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 })
 @javax.annotation.concurrent.Immutable
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.12.0-SNAPSHOT")
-public class AdditionalPropertiesBoolean extends HashMap<String, Boolean> {
+public class AdditionalPropertiesBoolean {
   public static final String JSON_PROPERTY_NAME = "name";
   @javax.annotation.Nullable
   private String name;
 
   public AdditionalPropertiesBoolean() {
-
   }
 
   public AdditionalPropertiesBoolean name(@javax.annotation.Nullable String name) {
@@ -134,8 +131,8 @@ public class AdditionalPropertiesBoolean extends HashMap<String, Boolean> {
   public String toString() {
     StringBuilder sb = new StringBuilder();
     sb.append("class AdditionalPropertiesBoolean {\n");
-    sb.append("    ").append(toIndentedString(super.toString())).append("\n");
     sb.append("    name: ").append(toIndentedString(name)).append("\n");
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
     sb.append("}");
     return sb.toString();
   }

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/model/AdditionalPropertiesInteger.java

@@ -28,8 +28,6 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.fasterxml.jackson.annotation.JsonValue;
 import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
-import java.util.HashMap;
-import java.util.Map;
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 
@@ -41,13 +39,12 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 })
 @javax.annotation.concurrent.Immutable
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.12.0-SNAPSHOT")
-public class AdditionalPropertiesInteger extends HashMap<String, Integer> {
+public class AdditionalPropertiesInteger {
   public static final String JSON_PROPERTY_NAME = "name";
   @javax.annotation.Nullable
   private String name;
 
   public AdditionalPropertiesInteger() {
-
   }
 
   public AdditionalPropertiesInteger name(@javax.annotation.Nullable String name) {
@@ -134,8 +131,8 @@ public class AdditionalPropertiesInteger extends HashMap<String, Integer> {
   public String toString() {
     StringBuilder sb = new StringBuilder();
     sb.append("class AdditionalPropertiesInteger {\n");
-    sb.append("    ").append(toIndentedString(super.toString())).append("\n");
     sb.append("    name: ").append(toIndentedString(name)).append("\n");
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
     sb.append("}");
     return sb.toString();
   }

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/model/AdditionalPropertiesNumber.java

@@ -29,8 +29,6 @@ import com.fasterxml.jackson.annotation.JsonValue;
 import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
 import java.math.BigDecimal;
-import java.util.HashMap;
-import java.util.Map;
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 
@@ -42,13 +40,12 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 })
 @javax.annotation.concurrent.Immutable
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.12.0-SNAPSHOT")
-public class AdditionalPropertiesNumber extends HashMap<String, BigDecimal> {
+public class AdditionalPropertiesNumber {
   public static final String JSON_PROPERTY_NAME = "name";
   @javax.annotation.Nullable
   private String name;
 
   public AdditionalPropertiesNumber() {
-
   }
 
   public AdditionalPropertiesNumber name(@javax.annotation.Nullable String name) {
@@ -135,8 +132,8 @@ public class AdditionalPropertiesNumber extends HashMap<String, BigDecimal> {
   public String toString() {
     StringBuilder sb = new StringBuilder();
     sb.append("class AdditionalPropertiesNumber {\n");
-    sb.append("    ").append(toIndentedString(super.toString())).append("\n");
     sb.append("    name: ").append(toIndentedString(name)).append("\n");
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
     sb.append("}");
     return sb.toString();
   }

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/model/AdditionalPropertiesObject.java

@@ -28,7 +28,6 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.fasterxml.jackson.annotation.JsonValue;
 import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
-import java.util.HashMap;
 import java.util.Map;
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.annotation.JsonTypeName;
@@ -41,13 +40,12 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 })
 @javax.annotation.concurrent.Immutable
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.12.0-SNAPSHOT")
-public class AdditionalPropertiesObject extends HashMap<String, Map> {
+public class AdditionalPropertiesObject {
   public static final String JSON_PROPERTY_NAME = "name";
   @javax.annotation.Nullable
   private String name;
 
   public AdditionalPropertiesObject() {
-
   }
 
   public AdditionalPropertiesObject name(@javax.annotation.Nullable String name) {
@@ -134,8 +132,8 @@ public class AdditionalPropertiesObject extends HashMap<String, Map> {
   public String toString() {
     StringBuilder sb = new StringBuilder();
     sb.append("class AdditionalPropertiesObject {\n");
-    sb.append("    ").append(toIndentedString(super.toString())).append("\n");
     sb.append("    name: ").append(toIndentedString(name)).append("\n");
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
     sb.append("}");
     return sb.toString();
   }

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/model/AdditionalPropertiesString.java

@@ -28,8 +28,6 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.fasterxml.jackson.annotation.JsonValue;
 import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
-import java.util.HashMap;
-import java.util.Map;
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 
@@ -41,13 +39,12 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 })
 @javax.annotation.concurrent.Immutable
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.12.0-SNAPSHOT")
-public class AdditionalPropertiesString extends HashMap<String, String> {
+public class AdditionalPropertiesString {
   public static final String JSON_PROPERTY_NAME = "name";
   @javax.annotation.Nullable
   private String name;
 
   public AdditionalPropertiesString() {
-
   }
 
   public AdditionalPropertiesString name(@javax.annotation.Nullable String name) {
@@ -134,8 +131,8 @@ public class AdditionalPropertiesString extends HashMap<String, String> {
   public String toString() {
     StringBuilder sb = new StringBuilder();
     sb.append("class AdditionalPropertiesString {\n");
-    sb.append("    ").append(toIndentedString(super.toString())).append("\n");
     sb.append("    name: ").append(toIndentedString(name)).append("\n");
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
     sb.append("}");
     return sb.toString();
   }

samples/client/petstore/java/feign/src/main/java/org/openapitools/client/model/NullableClass.java

@@ -57,7 +57,7 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
   NullableClass.JSON_PROPERTY_OBJECT_ITEMS_NULLABLE
 })
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.12.0-SNAPSHOT")
-public class NullableClass extends HashMap<String, Object> {
+public class NullableClass {
   public static final String JSON_PROPERTY_INTEGER_PROP = "integer_prop";
   private JsonNullable<Integer> integerProp = JsonNullable.<Integer>undefined();
 
@@ -97,7 +97,6 @@ public class NullableClass extends HashMap<String, Object> {
   private Map<String, Object> objectItemsNullable = new HashMap<>();
 
   public NullableClass() {
-
   }
 
   public NullableClass integerProp(@javax.annotation.Nullable Integer integerProp) {
@@ -620,7 +619,7 @@ public class NullableClass extends HashMap<String, Object> {
         equalsNullable(this.objectNullableProp, nullableClass.objectNullableProp) &&
         equalsNullable(this.objectAndItemsNullableProp, nullableClass.objectAndItemsNullableProp) &&
         Objects.equals(this.objectItemsNullable, nullableClass.objectItemsNullable) &&
-        super.equals(o);
+        Objects.equals(this.additionalProperties, nullableClass.additionalProperties);
   }
 
   private static <T> boolean equalsNullable(JsonNullable<T> a, JsonNullable<T> b) {
@@ -629,7 +628,7 @@ public class NullableClass extends HashMap<String, Object> {
 
   @Override
   public int hashCode() {
-    return Objects.hash(hashCodeNullable(integerProp), hashCodeNullable(numberProp), hashCodeNullable(booleanProp), hashCodeNullable(stringProp), hashCodeNullable(dateProp), hashCodeNullable(datetimeProp), hashCodeNullable(arrayNullableProp), hashCodeNullable(arrayAndItemsNullableProp), arrayItemsNullable, hashCodeNullable(objectNullableProp), hashCodeNullable(objectAndItemsNullableProp), objectItemsNullable, super.hashCode());
+    return Objects.hash(hashCodeNullable(integerProp), hashCodeNullable(numberProp), hashCodeNullable(booleanProp), hashCodeNullable(stringProp), hashCodeNullable(dateProp), hashCodeNullable(datetimeProp), hashCodeNullable(arrayNullableProp), hashCodeNullable(arrayAndItemsNullableProp), arrayItemsNullable, hashCodeNullable(objectNullableProp), hashCodeNullable(objectAndItemsNullableProp), objectItemsNullable, additionalProperties);
   }
 
   private static <T> int hashCodeNullable(JsonNullable<T> a) {
@@ -643,7 +642,6 @@ public class NullableClass extends HashMap<String, Object> {
   public String toString() {
     StringBuilder sb = new StringBuilder();
     sb.append("class NullableClass {\n");
-    sb.append("    ").append(toIndentedString(super.toString())).append("\n");
     sb.append("    integerProp: ").append(toIndentedString(integerProp)).append("\n");
     sb.append("    numberProp: ").append(toIndentedString(numberProp)).append("\n");
     sb.append("    booleanProp: ").append(toIndentedString(booleanProp)).append("\n");
@@ -656,6 +654,7 @@ public class NullableClass extends HashMap<String, Object> {
     sb.append("    objectNullableProp: ").append(toIndentedString(objectNullableProp)).append("\n");
     sb.append("    objectAndItemsNullableProp: ").append(toIndentedString(objectAndItemsNullableProp)).append("\n");
     sb.append("    objectItemsNullable: ").append(toIndentedString(objectItemsNullable)).append("\n");
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
     sb.append("}");
     return sb.toString();
   }

samples/client/petstore/java/feign/src/main/java/org/openapitools/client/model/TestInlineFreeformAdditionalPropertiesRequest.java

@@ -24,8 +24,6 @@ import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.fasterxml.jackson.annotation.JsonValue;
-import java.util.HashMap;
-import java.util.Map;
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 
@@ -37,13 +35,12 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 })
 @JsonTypeName("testInlineFreeformAdditionalProperties_request")
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.12.0-SNAPSHOT")
-public class TestInlineFreeformAdditionalPropertiesRequest extends HashMap<String, Object> {
+public class TestInlineFreeformAdditionalPropertiesRequest {
   public static final String JSON_PROPERTY_SOME_PROPERTY = "someProperty";
   @javax.annotation.Nullable
   private String someProperty;
 
   public TestInlineFreeformAdditionalPropertiesRequest() {
-
   }
 
   public TestInlineFreeformAdditionalPropertiesRequest someProperty(@javax.annotation.Nullable String someProperty) {
@@ -125,20 +122,20 @@ public class TestInlineFreeformAdditionalPropertiesRequest extends HashMap<Strin
     }
     TestInlineFreeformAdditionalPropertiesRequest testInlineFreeformAdditionalPropertiesRequest = (TestInlineFreeformAdditionalPropertiesRequest) o;
     return Objects.equals(this.someProperty, testInlineFreeformAdditionalPropertiesRequest.someProperty) &&
-        super.equals(o);
+        Objects.equals(this.additionalProperties, testInlineFreeformAdditionalPropertiesRequest.additionalProperties);
   }
 
   @Override
   public int hashCode() {
-    return Objects.hash(someProperty, super.hashCode());
+    return Objects.hash(someProperty, additionalProperties);
   }
 
   @Override
   public String toString() {
     StringBuilder sb = new StringBuilder();
     sb.append("class TestInlineFreeformAdditionalPropertiesRequest {\n");
-    sb.append("    ").append(toIndentedString(super.toString())).append("\n");
     sb.append("    someProperty: ").append(toIndentedString(someProperty)).append("\n");
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
     sb.append("}");
     return sb.toString();
   }

samples/client/petstore/java/feign/src/test/java/org/openapitools/client/JacksonTest.java

@@ -0,0 +1,67 @@
+package org.openapitools.client;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.MapperFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.openapitools.client.model.TestInlineFreeformAdditionalPropertiesRequest;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class JacksonTest {
+
+    private ObjectMapper mapper;
+
+    @BeforeEach
+    void setUp() {
+        mapper = JsonMapper.builder()
+                // For determinist serialization results
+                .enable(MapperFeature.SORT_PROPERTIES_ALPHABETICALLY)
+                .enable(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS)
+                .build();
+    }
+
+    @Test
+    void testSerializeAdditionalProperties() throws JsonProcessingException {
+        // Given
+        TestInlineFreeformAdditionalPropertiesRequest model = new TestInlineFreeformAdditionalPropertiesRequest()
+                .someProperty("value")
+                .putAdditionalProperty("someString", "someValue")
+                .putAdditionalProperty("someNumber", 1.23)
+                .putAdditionalProperty("someBoolean", true);
+
+        // When
+        String string = mapper.writeValueAsString(model);
+
+        // Then
+        String expectedString = "{\"someProperty\":\"value\",\"someBoolean\":true,\"someNumber\":1.23,\"someString\":\"someValue\"}";
+        assertEquals(expectedString, string);
+    }
+
+    @Test
+    void testDeserializeAdditionalProperties() throws JsonProcessingException {
+        // Given
+        String string = "{\"someProperty\":\"value\",\"someBoolean\":true,\"someNumber\":1.23,\"someString\":\"someValue\"}";
+
+        // When
+        TestInlineFreeformAdditionalPropertiesRequest model = mapper.readValue(
+                string,
+                TestInlineFreeformAdditionalPropertiesRequest.class
+        );
+
+        // Then
+        TestInlineFreeformAdditionalPropertiesRequest expectedModel = new TestInlineFreeformAdditionalPropertiesRequest()
+                .someProperty("value")
+                .putAdditionalProperty("someString", "someValue")
+                .putAdditionalProperty("someNumber", 1.23)
+                .putAdditionalProperty("someBoolean", true);
+        assertEquals(expectedModel, model);
+
+        TestInlineFreeformAdditionalPropertiesRequest invalidModel = new TestInlineFreeformAdditionalPropertiesRequest()
+                .someProperty("value");
+        assertNotEquals(invalidModel, model);
+    }
+}