[ALL] [3.0] Vars empty when additionalProperties used

Description

When defining a model with some explicitly defined properties and additionalProperties, ex.

  Org:
    type: "object"
    required:
    - "id"
    - "name"
    properties:
      id:
        type: "string"
      name:
        type: "string"
    additionalProperties:
      type: "object"

, all *vars properties in swagger-codegen are empty (as verified by -DdebugModels=true), ex.

{
  "importPath" : "from swagger_client.models.org import Org",
  "model" : {
    "vendorExtensions" : {
      "x-is-alias" : false,
      "x-is-container" : true,
      "x-is-map-container" : true
    },
    "parent" : "dict<String, object>",
    "name" : "Org",
    "classname" : "Org",
    "classVarName" : "org",
    "modelJson" : "{\n  \"required\" : [ \"id\", \"name\" ],\n  \"type\" : \"object\",\n  \"properties\" : {\n    \"id\" : {\n      \"type\" : \"string\"\n    },\n    \"name\" : {\n      \"type\" : \"string\"\n    }\n  },\n  \"additionalProperties\" : {\n    \"type\" : \"object\",\n    \"properties\" : { }\n  }\n}",
    "classFilename" : "org",
    "vars" : [ ],
    "requiredVars" : [ ],
    "optionalVars" : [ ],
    "readOnlyVars" : [ ],
    "readWriteVars" : [ ],
    "allVars" : [ ],
    "parentVars" : [ ],
    "mandatory" : [ ],
    "allMandatory" : [ ],
    "imports" : [ ],
    "emptyVars" : false,
    "hasVars" : false,
    "hasOnlyReadOnly" : false,
    "hasMoreModels" : false,
    "hasEnums" : false,
    "hasRequired" : false,
    "hasOptional" : false,
    "hasChildren" : false,
    "hasHeaders" : false,
    "isString" : false,
    "isNumeric" : false,
    "isInteger" : false,
    "isLong" : false,
    "isNumber" : false,
    "isFloat" : false,
    "isDouble" : false,
    "isByteArray" : false,
    "isBoolean" : false,
    "isDate" : false,
    "isDateTime" : false,
    "isUuid" : false,
    "isDefault" : false,
    "isMapContainer" : true,
    "isListContainer" : false,
    "isMultipart" : false,
    "isResponseBinary" : false,
    "isResponseFile" : false,
    "isBinary" : false,
    "isFile" : false,
    "isEnum" : false,
    "isArrayModel" : false,
    "isAlias" : false,
    "isContainer" : true,
    "isNotContainer" : false,
    "isReadOnly" : false,
    "isCollectionFormatMulti" : false,
    "hasMore" : false,
    "isPrimitiveType" : false
  }
}

This results in swagger-codegen generating incomplete classes, ex:

package io.swagger.client.model;

import java.util.Objects;
import java.util.HashMap;
import java.util.Map;

/**
 * Org
 */

@javax.annotation.Generated(value = "io.swagger.codegen.v3.generators.java.JavaClientCodegen", date = "2019-01-22T16:05:29.386-08:00[America/Los_Angeles]")public class Org extends HashMap<String, Object> {
  @Override
  public boolean equals(java.lang.Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    return super.equals(o);
  }

  @Override
  public int hashCode() {
    return java.util.Objects.hash(super.hashCode());
  }

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("class Org {\n");
    sb.append("    ").append(toIndentedString(super.toString())).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(java.lang.Object o) {
    if (o == null) {
      return "null";
    }
    return o.toString().replace("\n", "\n    ");
  }

}

Compare to v2 where it generates a class that extends HashMap<String, Object> to accomodate but also has fields for explicitly defined properties.

Swagger-codegen version

3.0.4 and 3.0.5-SNAPSHOT

Swagger declaration file content or url

definitions:
  Org:
    type: "object"
    required:
    - "id"
    - "name"
    properties:
      id:
        type: "string"
      name:
        type: "string"
    additionalProperties:
      type: "object"

Command line used for generation

java -jar swagger-codegen-cli-3.0.4.jar generate -i /path/to/swagger.yaml -l java -o /var/tmp/java-api-client -DdebugModels=true

Steps to reproduce

See above.

Related issues/PRs

Suggest a fix/enhancement

I suggest populating *vars even when additionalProperties is enabled. This should resolve the issue as 2.0 already handled this case and the templates should already be able to handle them.

Start with the provided Swagger YAML and run the Java generation command using swagger-codegen 3.0.4 and -DdebugModels=true. Trace how models with additionalProperties populate the *vars collections and compare the generated Java model with the stated v2 behavior. Done means explicitly defined properties appear alongside the HashMap behavior in the generated class.