use model class for request body with additionalProperties (#16613)

* try out simple fix

* add test case

* generate samples

samples/client/petstore/java/feign/.openapi-generator/FILES

@@ -87,4 +87,5 @@ src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
 src/main/java/org/openapitools/client/model/SingleRefType.java
 src/main/java/org/openapitools/client/model/SpecialModelName.java
 src/main/java/org/openapitools/client/model/Tag.java
+src/main/java/org/openapitools/client/model/TestInlineFreeformAdditionalPropertiesRequest.java
 src/main/java/org/openapitools/client/model/User.java

samples/client/petstore/java/feign/api/openapi.yaml

@@ -1031,6 +1031,25 @@ paths:
       - fake
       x-content-type: application/json
       x-accepts: application/json
+  /fake/inline-freeform-additionalProperties:
+    post:
+      description: ""
+      operationId: testInlineFreeformAdditionalProperties
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/testInlineFreeformAdditionalProperties_request'
+        description: request body
+        required: true
+      responses:
+        "200":
+          description: successful operation
+      summary: test inline free-form additionalProperties
+      tags:
+      - fake
+      x-content-type: application/json
+      x-accepts: application/json
   /fake/nullable:
     post:
       description: ""
@@ -2191,6 +2210,12 @@ components:
       - param
       - param2
       type: object
+    testInlineFreeformAdditionalProperties_request:
+      additionalProperties: true
+      properties:
+        someProperty:
+          type: string
+      type: object
     uploadFileWithRequiredFile_request:
       properties:
         additionalMetadata:

samples/client/petstore/java/feign/src/main/java/org/openapitools/client/api/FakeApi.java

@@ -17,6 +17,7 @@ import java.time.OffsetDateTime;
 import org.openapitools.client.model.OuterComposite;
 import org.openapitools.client.model.OuterObjectWithEnumProperty;
 import org.openapitools.client.model.Pet;
+import org.openapitools.client.model.TestInlineFreeformAdditionalPropertiesRequest;
 import org.openapitools.client.model.User;
 
 import java.util.ArrayList;
@@ -811,6 +812,33 @@ public interface FakeApi extends ApiClient.Api {
 
 
 
+  /**
+   * test inline free-form additionalProperties
+   * 
+   * @param testInlineFreeformAdditionalPropertiesRequest request body (required)
+   */
+  @RequestLine("POST /fake/inline-freeform-additionalProperties")
+  @Headers({
+    "Content-Type: application/json",
+    "Accept: application/json",
+  })
+  void testInlineFreeformAdditionalProperties(TestInlineFreeformAdditionalPropertiesRequest testInlineFreeformAdditionalPropertiesRequest);
+
+  /**
+   * test inline free-form additionalProperties
+   * Similar to <code>testInlineFreeformAdditionalProperties</code> but it also returns the http response headers .
+   * 
+   * @param testInlineFreeformAdditionalPropertiesRequest request body (required)
+   */
+  @RequestLine("POST /fake/inline-freeform-additionalProperties")
+  @Headers({
+    "Content-Type: application/json",
+    "Accept: application/json",
+  })
+  ApiResponse<Void> testInlineFreeformAdditionalPropertiesWithHttpInfo(TestInlineFreeformAdditionalPropertiesRequest testInlineFreeformAdditionalPropertiesRequest);
+
+
+
   /**
    * test json serialization of form data
    * 

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

@@ -0,0 +1,157 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import java.util.Map;
+import java.util.HashMap;
+import com.fasterxml.jackson.annotation.JsonAnyGetter;
+import com.fasterxml.jackson.annotation.JsonAnySetter;
+import java.util.Objects;
+import java.util.Arrays;
+import com.fasterxml.jackson.annotation.JsonInclude;
+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;
+
+/**
+ * TestInlineFreeformAdditionalPropertiesRequest
+ */
+@JsonPropertyOrder({
+  TestInlineFreeformAdditionalPropertiesRequest.JSON_PROPERTY_SOME_PROPERTY
+})
+@JsonTypeName("testInlineFreeformAdditionalProperties_request")
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen")
+public class TestInlineFreeformAdditionalPropertiesRequest extends HashMap<String, Object> {
+  public static final String JSON_PROPERTY_SOME_PROPERTY = "someProperty";
+  private String someProperty;
+
+  public TestInlineFreeformAdditionalPropertiesRequest() {
+
+  }
+
+  public TestInlineFreeformAdditionalPropertiesRequest someProperty(String someProperty) {
+    
+    this.someProperty = someProperty;
+    return this;
+  }
+
+   /**
+   * Get someProperty
+   * @return someProperty
+  **/
+  @javax.annotation.Nullable
+  @JsonProperty(JSON_PROPERTY_SOME_PROPERTY)
+  @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
+
+  public String getSomeProperty() {
+    return someProperty;
+  }
+
+
+  @JsonProperty(JSON_PROPERTY_SOME_PROPERTY)
+  @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
+  public void setSomeProperty(String someProperty) {
+    this.someProperty = someProperty;
+  }
+
+  /**
+   * A container for additional, undeclared properties.
+   * This is a holder for any undeclared properties as specified with
+   * the 'additionalProperties' keyword in the OAS document.
+   */
+  private Map<String, Object> additionalProperties;
+
+  /**
+   * Set the additional (undeclared) property with the specified name and value.
+   * If the property does not already exist, create it otherwise replace it.
+   * @param key the name of the property
+   * @param value the value of the property
+   * @return self reference
+   */
+  @JsonAnySetter
+  public TestInlineFreeformAdditionalPropertiesRequest putAdditionalProperty(String key, Object value) {
+    if (this.additionalProperties == null) {
+        this.additionalProperties = new HashMap<String, Object>();
+    }
+    this.additionalProperties.put(key, value);
+    return this;
+  }
+
+  /**
+   * Return the additional (undeclared) properties.
+   * @return the additional (undeclared) properties
+   */
+  @JsonAnyGetter
+  public Map<String, Object> getAdditionalProperties() {
+    return additionalProperties;
+  }
+
+  /**
+   * Return the additional (undeclared) property with the specified name.
+   * @param key the name of the property
+   * @return the additional (undeclared) property with the specified name
+   */
+  public Object getAdditionalProperty(String key) {
+    if (this.additionalProperties == null) {
+        return null;
+    }
+    return this.additionalProperties.get(key);
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    TestInlineFreeformAdditionalPropertiesRequest testInlineFreeformAdditionalPropertiesRequest = (TestInlineFreeformAdditionalPropertiesRequest) o;
+    return Objects.equals(this.someProperty, testInlineFreeformAdditionalPropertiesRequest.someProperty) &&
+        super.equals(o);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(someProperty, super.hashCode());
+  }
+
+  @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("}");
+    return sb.toString();
+  }
+
+  /**
+   * Convert the given object to string with each line indented by 4 spaces
+   * (except the first line).
+   */
+  private String toIndentedString(Object o) {
+    if (o == null) {
+      return "null";
+    }
+    return o.toString().replace("\n", "\n    ");
+  }
+
+}
+

samples/client/petstore/java/feign/src/test/java/org/openapitools/client/model/TestInlineFreeformAdditionalPropertiesRequestTest.java

@@ -0,0 +1,47 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+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 org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for TestInlineFreeformAdditionalPropertiesRequest
+ */
+class TestInlineFreeformAdditionalPropertiesRequestTest {
+    private final TestInlineFreeformAdditionalPropertiesRequest model = new TestInlineFreeformAdditionalPropertiesRequest();
+
+    /**
+     * Model tests for TestInlineFreeformAdditionalPropertiesRequest
+     */
+    @Test
+    void testTestInlineFreeformAdditionalPropertiesRequest() {
+        // TODO: test TestInlineFreeformAdditionalPropertiesRequest
+    }
+
+    /**
+     * Test the property 'someProperty'
+     */
+    @Test
+    void somePropertyTest() {
+        // TODO: test someProperty
+    }
+
+}