[BUG] RAG processor throws null pointer exception

[ylwu-amzn]

What is the bug?
Run RAG processor on multi-node cluster without dedicated master node. Can see such error

Cannot invoke "java.lang.Integer.intValue()" because "this.interactionSize" is null

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Set up multi-node cluster with 3 nodes, all nodes have master and data role
2. Run RAG processor

What is the expected behavior?
Should not throw exception

What is your host/environment?

• OS: Linux
• Version 2.15

Do you have any screenshots?
No

Do you have any additional context?
Log

java.lang.NullPointerException: Cannot invoke "java.lang.Integer.intValue()" because "this.interactionSize" is null
    at org.opensearch.searchpipelines.questionanswering.generative.ext.GenerativeQAParameters.writeTo(GenerativeQAParameters.java:197)
    at org.opensearch.searchpipelines.questionanswering.generative.ext.GenerativeQAParamExtBuilder.writeTo(GenerativeQAParamExtBuilder.java:75)

[pyek-bot]

Can you assign this to me?

[ylwu-amzn]

Sure, assigned to you @pyek-bot

[pyek-bot]

Bug is currently not reproduceable on 2.16 or 2.17. It has been fixed, so this should not be a blocker for the new version. However, determining the exact change will require further investigation to backport to 2.15.

*Edit: bug appears to be flaky and intermittent in nature on all versions, will require further investigation