[typescript-rxjs][client] Unnecessary imports occurs when using allOf

[tanmen]

fixes #4629

Hello.
When using rxjs, a warning occurred in unused import.
I tried to fix it, so please take a look if you like.

Before

// tslint:disable
/**
 * My application
 * My application
 *
 * 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.
 */

 import {
     Box,
     Response,
 } from './';

 /**
  * @export
  * @interface BoxResponse
  */
 export interface BoxResponse extends Box, Response{
     /**
      * @type {string}
      * @memberof BoxResponse
      */
     status?: BoxResponseStatusEnum;
     /**
      * @type {number}
      * @memberof BoxResponse
      */
     id?: number;
     /**
      * @type {string}
      * @memberof BoxResponse
      */
     name?: string;
 }

 /**
  * @export
  * @enum {string}
  */
 export enum BoxResponseStatusEnum {
     Success = 'success',
     Error = 'error'
 }

After

// tslint:disable
/**
 * Myroad api
 * Myroad user api document
 *
 * 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.
 */

import {
    Box,
    Response,
} from './';

/**
 * @type BoxesResponse
 * @export
 */
export type BoxesResponse = Box & Response;

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@TiFu (2017/07) @taxpon (2017/07) @sebastianhaas (2017/07) @kenisteward (2017/07) @Vrolijkx (2017/09) @macjohnny (2018/01) @nicokoenig (2018/09) @topce (2018/10) @akehir (2019/07) @petejohansonxo (2019/11)

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[macjohnny]

cc @denyo

[denyo]

Thanks, looks good.
When I was trying something around inheritance a couple of months ago I added supportsMultipleInheritance = true; to the Java code which also had some effect but I can't recall which.

[tanmen]

@denyo
sorry my response to late.
i so happy for your review!

@macjohnny
so thank you management this pr!!

[wing328]

@tanmen thanks for the PR, which has been included in the v4.2.2 release: https://twitter.com/oas_generator/status/1201432648544972800