private boolean validateHeaderSufficientlyAheadOfParent(
      final long timestamp, final long parentTimestamp) {
    final long secondsSinceParent = timestamp - parentTimestamp;
    if (secondsSinceParent < minimumSecondsSinceParent) {
      LOG.info(
          "Invalid block header: timestamp {} is only {} seconds newer than parent timestamp {}. Minimum {} seconds",
          timestamp,
          secondsSinceParent,
          parentTimestamp,
          minimumSecondsSinceParent);
      return false;
    }

    return true;
  }
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