[BUG] Unknown Parameter [if_seq_num] Error When Using Optimistic Concurrency Control

[noname4life]

What is the bug?

Optimistic concurrency control using the BulkIndexerItem struct fails and returns a 400 Bad Request error with the following type and reason
Type: "illegal_argument_exception"
Reason: "Action/metadata line [1] contains an unknown parameter [if_seq_num]"

How can one reproduce the bug?

1. Create a BulkIndexer using NewBulkIndexer
2. Create a BulkIndexerItem with the fields IfSeqNum and IfPrimaryTerm filled up
3. Call the add() method of the BulkIndexer
4. Call the Close() method of the BulkIndexer to flush the BulkIndexerItem

What is the expected behavior?

The document should be indexed without any errors being returned

What is your host/environment?

Windows 10
GoLang version 1.18
github.com/opensearch-project/opensearch-go v 1.1.0

Do you have any additional context?

This is caused by the use of "if_seq_num" in the following line. This should be replaced with "if_seq_no" based on the following reference in elastic search regarding optimistic concurrency control.