code: public ApiResponse<RefreshTokenResponse> refreshTokenWithHttpInfo(String grantType, String refreshToken) throws ApiException {
          com.squareup.okhttp.Call call = refreshTokenValidateBeforeCall(grantType, refreshToken, null, null);
          Type localVarReturnType = new TypeToken<RefreshTokenResponse>(){}.getType();
          return apiClient.execute(call, localVarReturnType);
      }
docs: Refresh Token
  Refresh Token
  @param grantType Grant Type. (required)
  @param refreshToken Refresh Token. (required)
  @return ApiResponse&lt;RefreshTokenResponse&gt;
  @throws ApiException If fail to call the API, e.g. server error or cannot deserialize the response body