json array not generating proper model classes

Description

I am trying to generate swagger api from the following json:
https://watson-api-explorer.mybluemix.net/listings/conversation-v1.json

but it's not generating proper model classes, where ever it has following similar json:

 "CreateWorkspace": {
      "allOf": [
        {
          "$ref": "#/definitions/BaseEntity"
        }
      ],
      "x-java-builder": true
    },

Generated Model Class doesn't have reference to BaseEntity Class

import java.util.Objects;
import com.ibm.mfp.adapters.sample.model.BaseEntity;


/**
 * CreateWorkspace
 */
@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2017-04-19T17:14:05.018+05:30")
public class CreateWorkspace   {

  @Override
  public boolean equals(java.lang.Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    return true;
  }

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

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("class CreateWorkspace {\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    ");
  }
}

json looks correct only, as i am using watson json mentioned in above link.

Swagger-codegen version

2.2.2

Swagger declaration file content or url

https://watson-api-explorer.mybluemix.net/listings/conversation-v1.json

Reproduce the issue with the linked Watson conversation-v1.json using Swagger-codegen 2.2.2 and inspect the generated CreateWorkspace and BaseEntity classes. Start at the JavaClientCodegen path named in the generated annotation; done means the generated CreateWorkspace model preserves the allOf reference to BaseEntity.