[BUG] NodeInfo required fields can be null in some instances

[dancristiancecoi]

What is the bug?

As described in opensearch-project/opensearch-java#1129, some NodeInfo fields (Host, Ip, TransportAddress) that are listed as required can be null when connected to Amazon OpenSearch Service.

How can one reproduce the bug?

Perform a NodeInfoRequest (or equivalent) against an Amazon OpenSearch Service cluster. Those fields will be returned empty.

Proposed fix

NodeInfo.Host, NodeInfo.Ip, NodeInfo.TransportAddress should not be listed as required in the spec

Additional context:

Related Issue:

• [BUG] NodeInfoRequest fails when connecting to Amazon OpenSearch Service  opensearch-java#1129

I can provide a PR if the above proposed fix is acceptable

[dblock]

I fixed this in #483. After that PR the spec runs clean against AOS 2.13.