I haven't looked at the source code, but I'm not sure that the sequence number will make much sense after the request has been parsed into a HTTP::Request anymore. You haven't shown any code that works, but from looking at the data structure, I guess that

$self_eclipse_1->tcp_connection->sequence_start
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or

$self_eclipse_1->tcp_connection->last_ack
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might give you the numbers. Maybe you want to read the source code or perldsc or References Quick Reference to learn about how to access the values.