private boolean validateTimestamp(final long timestamp) {
    return validateHeaderNotAheadOfCurrentSystemTime(timestamp);
  }
Responsible for ensuring the timestamp of a block is not more than "acceptableClockDriftSeconds"
into the future.
ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/headervalidationrules/TimestampBoundedByFutureParameter.java