@JsonSubTypes not in the generated java code from openapi 3.0.1 definition file

Hi,

I generated the api definition file (openapi "3.0.1") from jaxrs code with maven plugin:

                <groupId>io.swagger.core.v3</groupId>
                <artifactId>swagger-maven-plugin</artifactId>
                <version>2.0.8</version>

I used the following maven plugin for generating java class from the above api definition file.

    <groupId>org.openapitools</groupId>
    <artifactId>openapi-generator-maven-plugin</artifactId>
    <version>4.0.0-beta3</version>

There are a couple of issues. To illustrate the issues. The following is a section of the definition file (generated from swagger-maven-plugin ):

 "openapi" : "3.0.1",
  "components":{
   "schemas":{
      "Message" : {
        "type" : "object",
        "properties" : {
          "msgId" : {
            "type" : "string"
          },
          "timestamp" : {
            "type" : "string",
            "format" : "date-time"
          },
        "discriminator" : {
          "propertyName" : "type",
          "mapping" : {
            "text" : "#/components/schemas/TextMessage",
            "file" : "#/components/schemas/FileMessage"
          }
        }
      }
...

}

The following are some issues:
(1) There was not @JsonSubTypes in the generated java file
(2) The OffsetDateTime is from org.threeten.bp.OffsetDateTime instead of java.time.OffsetDateTime
(3) It import ApiModel and ApiModelProperty (openApi v2.0)
(4) it annotates fields with com.google.gson.annotations.SerializedName, and not
@JsonProperty

Is there special configuration that allow the generated code very close to the original code?

Thanks

Wayne

Start with the OpenAPI 3.0.1 definition and the openapi-generator-maven-plugin 4.0.0-beta3 configuration described in the issue. Investigate how the Java generator handles discriminators, date-time types, and annotation libraries. Done means determining whether configuration or generator changes are needed for the four reported outputs.