docs: public void finishFlow(final String code, final String state) throws ApiException {
          if (account == null)
              throw new IllegalArgumentException("Auth is not set");
          if (codeVerifier == null)
              throw new IllegalArgumentException("code_verifier is not set");
          if (account.getClientId() == null)
              throw new IllegalArgumentException("client_id is not set");
          StringBuilder builder = new StringBuilder();
          builder.append("grant_type=");
          builder.append(encode("authorization_code"));
          builder.append("&client_id=");
          builder.append(encode(account.getClientId()));
          builder.append("&code=");
          builder.append(encode(code));
          builder.append("&code_verifier=");
          builder.append(encode(codeVerifier));
          update(account, builder.toString());
      }