message: use spread operator for setMaxFee
diff: @@ -200,7 +200,7 @@ export abstract class Transaction {
  * @returns {TransferTransaction}
  */
  public setMaxFee(feeMultiplier: number): Transaction {
  - return Object.assign({__proto__: Object.getPrototypeOf(this)}, this, {maxFee: UInt64.fromUint(this.size * feeMultiplier)});
  + return {...Object.getPrototypeOf(this), maxFee: UInt64.fromUint(this.size * feeMultiplier)};
  }
  /**
  