message: implement last ledger sequence
diff: @@ -11,7 +11,7 @@ import {
  import { AccountAddress } from "../generated/rpc/v1/amount_pb";
  import { GetTxRequest, GetTxResponse } from "../generated/rpc/v1/tx_pb";
  import { XRPDropsAmount } from "xpring-common-js/build/generated/rpc/v1/amount_pb";
  -import { GetFeeRequest } from "../generated/rpc/v1/fee_pb";
  +import { GetFeeRequest, GetFeeResponse } from "../generated/rpc/v1/fee_pb";
  /* global BigInt */
  @@ -164,7 +164,8 @@ class DefaultXpringClient implements XpringClientDecorator {
  }
  public async getLastValidatedLedgerSequence(): Promise<number> {
  - throw new Error(XpringClientErrorMessages.unimplemented);
  + const getFeeResponse = await this.getFee();
  + return getFeeResponse.getLedgerCurrentIndex();
  }
  public async getRawTransactionStatus(
  @@ -178,10 +179,8 @@ class DefaultXpringClient implements XpringClientDecorator {
  return new GetTxResponseWrapper(getTxResponse);
  }
  - private async getFee(): Promise<XRPDropsAmount> {
  - const getFeeRequest = new GetFeeRequest();
  -
  - const getFeeResponse = await this.networkClient.getFee(getFeeRequest);
  + private async getMinimumFee(): Promise<XRPDropsAmount> {
  + const getFeeResponse = await this.getFee();
  const fee = getFeeResponse.getDrops();
  if (!fee) {
  throw new Error(XpringClientErrorMessages.malformedResponse);
  @@ -194,6 +193,11 @@ class DefaultXpringClient implements XpringClientDecorator {
  return minimumFee;
  }
  +
  + private async getFee(): Promise<GetFeeResponse> {
  + const getFeeRequest = new GetFeeRequest();
  + return await this.networkClient.getFee(getFeeRequest);
  + }
  }
  export default DefaultXpringClient;
  