[BUG] model search doesn't recognize _source field

[wanglam]

What is the bug?
I am using the model search API to get all trained model. But the API still response all fields even I pass _source field in the query body. The query like:

POST /_plugins/_ml/models/_search
{
  "_source": ["name"],
  "query":{
    "match_all":{
      
    }
  }
}

How can one reproduce the bug?
Just use query like

POST /_plugins/_ml/models/_search
{
  "_source": ["name"],
  "query":{
    "match_all":{
      
    }
  }
}

What is the expected behavior?
Should only response name field in the response _source.

What is your host/environment?

• OS: [e.g. iOS]
• Version [e.g. 22]
• Plugins

Do you have any screenshots?

The model_content field is also returned.

Do you have any additional context?
Nope.

[ylwu-amzn]

Thanks for reporting this bug. This is caused by source context rewrite in AbstractMLSearchAction.java. We should keep original fetch source in method getSourceContext

@rbhavna can you help fix this bug?