[FEATURE]Support of new k-NN query parameter, expand_nested_docs

[heemin32]

Is your feature request related to a problem?

In opensearch-project/k-NN#2283, a new parameter expand_nested_docs is added in k-nn query to support multi inner hits. I want it to be supported in neural search.

What solution would you like?

Support of expand_nested_docs parameter in neural search.

What alternatives have you considered?

Not supporting it.

Do you have any additional context?

Similar change has been made for a support of ef_search parameter. #814

[bzhangam]

I'll work on this item.

[bzhangam]

Hi @heemin32. I notice that in k-nn query the new field is called EXPAND_NESTED = "expand_nested_docs" but here you mention we want to add a new parameter extend_nested_docs. Wonder why we intend to use a different name? Should we also use expand_nested_docs in neural search for consistency?

[heemin32]

Hi @heemin32. I notice that in k-nn query the new field is called EXPAND_NESTED = "expand_nested_docs" but here you mention we want to add a new parameter extend_nested_docs. Wonder why we intend to use a different name? Should we also use expand_nested_docs in neural search for consistency?

My bad. we will use same name. expand_nested_docs