How to use the long.fromBytesBE function in long

public static longFromBigInt(number: BN) {
        // Emulate Java BigInteger.longValue(), following the spec at 5.1.3 https://docs.oracle.com/javase/specs/jls/se7/html/jls-5.html
        let byteLength = Math.max(8, number.byteLength())
        const bytes = number.toTwos(8 * byteLength).toArray('be', byteLength)
        const truncatedBytes = bytes.slice(bytes.length - 8, bytes.length)
        return Long.fromBytesBE(truncatedBytes)
    }

public static fromByteArray(bytes: Buffer): any {
        // Read 1 byte for type
        let type = bytes.readUInt8(0)
        // Read 4 bytes for length
        let length = bytes.readUInt32BE(1)

        // Switch on type
        switch (type) {
            case DataTypes.BOOLEAN: {
                return bytes.readUInt8(5) ? true : false
            }
            case DataTypes.NUMBER: {
                return Long.fromBytesBE([...bytes.slice(5, 13)]).toNumber()
            }
            case DataTypes.STRING: {
                return bytes.slice(5, 5 + length).toString('utf8')
            }
            case DataTypes.BYTES: {
                return new RadixBase64(bytes.slice(5, 5 + length))
            }
            case DataTypes.OBJECT: {
                return this.fromObjectByteArray(bytes)
            }
            case DataTypes.ARRAY: {
                let output: Array = []
                let offset = 5

                while (offset < length) {
                    // Read 2nd to 5th bytes to find out the length of the value

);
      log.mgmt(
        "[%s] Acquiring lock to get the management req res link.",
        this._context.namespace.connectionId
      );
      await defaultLock.acquire(this.managementLock, () => {
        return this._init();
      });
      const result = await this._mgmtReqResLink!.sendRequest(request);
      const sequenceNumbers = result.body[Constants.sequenceNumbers];
      const sequenceNumbersAsLong = [];
      for (let i = 0; i < sequenceNumbers.length; i++) {
        if (typeof sequenceNumbers[i] === "number") {
          sequenceNumbersAsLong.push(Long.fromNumber(sequenceNumbers[i]));
        } else {
          sequenceNumbersAsLong.push(Long.fromBytesBE(sequenceNumbers[i]));
        }
      }
      return sequenceNumbersAsLong;
    } catch (err) {
      const error = translate(err);
      log.error(
        "An error occurred while sending the request to schedule messages to " +
          "$management endpoint: %O",
        error
      );
      throw error;
    }
  }

if (msg.message_annotations[Constants.scheduledEnqueueTime] != null) {
      sbmsg.scheduledEnqueueTimeUtc = msg.message_annotations[Constants.scheduledEnqueueTime];
    }
  }

  const props: any = {};
  if (msg.message_annotations != null) {
    if (msg.message_annotations[Constants.deadLetterSource] != null) {
      props.deadLetterSource = msg.message_annotations[Constants.deadLetterSource];
    }
    if (msg.message_annotations[Constants.enqueueSequenceNumber] != null) {
      props.enqueuedSequenceNumber = msg.message_annotations[Constants.enqueueSequenceNumber];
    }
    if (msg.message_annotations[Constants.sequenceNumber] != null) {
      if (Buffer.isBuffer(msg.message_annotations[Constants.sequenceNumber])) {
        props.sequenceNumber = Long.fromBytesBE(msg.message_annotations[Constants.sequenceNumber]);
      } else {
        props.sequenceNumber = Long.fromNumber(msg.message_annotations[Constants.sequenceNumber]);
      }
    }
    if (msg.message_annotations[Constants.enqueuedTime] != null) {
      props.enqueuedTimeUtc = new Date(msg.message_annotations[Constants.enqueuedTime] as number);
    }
    if (msg.message_annotations[Constants.lockedUntil] != null) {
      props.lockedUntilUtc = new Date(msg.message_annotations[Constants.lockedUntil] as number);
    }
  }
  if (msg.ttl != null && msg.ttl >= Constants.maxDurationValue - props.enqueuedTimeUtc.getTime()) {
    props.expiresAtUtc = new Date(Constants.maxDurationValue);
  } else {
    props.expiresAtUtc = new Date(props.enqueuedTimeUtc.getTime() + msg.ttl!);
  }

export function convertTicksToDate(buf: number[]): Date {
  const epochMicroDiff: number = 621355968000000000;
  const longValue: Long = Long.fromBytesBE(buf);
  const timeInMS = longValue
    .sub(epochMicroDiff)
    .div(10000)
    .toNumber();
  const result = new Date(timeInMS);
  log.utils("The converted date is: %s", result.toString());
  return result;
}

if (msg.message_annotations[Constants.scheduledEnqueueTime] != null) {
      sbmsg.scheduledEnqueueTimeUtc = msg.message_annotations[Constants.scheduledEnqueueTime];
    }
  }

  const props: any = {};
  if (msg.message_annotations != null) {
    if (msg.message_annotations[Constants.deadLetterSource] != null) {
      props.deadLetterSource = msg.message_annotations[Constants.deadLetterSource];
    }
    if (msg.message_annotations[Constants.enqueueSequenceNumber] != null) {
      props.enqueuedSequenceNumber = msg.message_annotations[Constants.enqueueSequenceNumber];
    }
    if (msg.message_annotations[Constants.sequenceNumber] != null) {
      if (Buffer.isBuffer(msg.message_annotations[Constants.sequenceNumber])) {
        props.sequenceNumber = Long.fromBytesBE(msg.message_annotations[Constants.sequenceNumber]);
      } else {
        props.sequenceNumber = Long.fromNumber(msg.message_annotations[Constants.sequenceNumber]);
      }
    }
    if (msg.message_annotations[Constants.enqueuedTime] != null) {
      props.enqueuedTimeUtc = new Date(msg.message_annotations[Constants.enqueuedTime] as number);
    }
    if (msg.message_annotations[Constants.lockedUntil] != null) {
      props.lockedUntilUtc = new Date(msg.message_annotations[Constants.lockedUntil] as number);
    }
  }
  if (msg.ttl != null && msg.ttl >= Constants.maxDurationValue - props.enqueuedTimeUtc.getTime()) {
    props.expiresAtUtc = new Date(Constants.maxDurationValue);
  } else {
    props.expiresAtUtc = new Date(props.enqueuedTimeUtc.getTime() + msg.ttl!);
  }