private boolean validateTimestamp(final long timestamp, final long parentTimestamp) {
    return validateHeaderSufficientlyAheadOfParent(timestamp, parentTimestamp);
  }
Responsible for ensuring the timestamp of a block is newer than its parent.
ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/headervalidationrules/TimestampMoreRecentThanParent.java