Last 'other' bucket on terms agg broken when first bucket is split on a term containing a dash (-)

[lukeelmers]

Kibana version: tested on master & 7.2

The terms_other_bucket_helper we use for dealing with "other" and "missing" buckets in terms aggregations has a weird edge case where splitting on terms containing a dash/hyphen (-) can cause the other bucket to be missed.

I suspect this is due to the fact that we are splitting on dashes in bucket keys as a way to manage nested buckets:

kibana/src/legacy/ui/public/agg_types/buckets/_terms_other_bucket_helper.js

Lines 49 to 52 in e48e078

	const getAggResultBuckets = (aggConfigs, response, aggWithOtherBucket, key) => {
	const keyParts = key.split('-');
	let responseAgg = response;
	for (const i in keyParts) {

For data that is expected to contain dashes, this can cause "other" buckets to fail to display in visualizations.

Steps to reproduce:

1. Using the dev console, ingest documents from each of the two data sets todos1 and todos2 (listed below)
2. Create index patterns todos1* and index pattern todos2*
3. Create the same data table visualization against each index pattern (though this is reproducible on other vis types too):
   • split rows with terms aggregation on status.keyword, size 5
   • split rows with terms aggregation on task.keyword, size 1, "group other values" enabled
4. Compare the two and notice that the data from todos1 is missing other buckets due to the dashes contained in the status.keyword data. Everything from todos2 behaves as expected.
5. You'll notice the same issue is visible in the inspector data, since the other buckets are simply missing from the tabified data.

Visualization: todos1 (broken)

Visualization: todos2 (works)

Sample data: todos1 (broken)

POST todos1/_doc
{
  "status": "to-do",
  "task": "A"
}

POST todos1/_doc
{
  "status": "to-do",
  "task": "B"
}

POST todos1/_doc
{
  "status": "to-do",
  "task": "C"
}

POST todos1/_doc
{
  "status": "to-do",
  "task": "C"
}

POST todos1/_doc
{
  "status": "in-progress",
  "task": "D"
}

POST todos1/_doc
{
  "status": "in-progress",
  "task": "E"
}

POST todos1/_doc
{
  "status": "in-progress",
  "task": "F"
}

POST todos1/_doc
{
  "status": "done",
  "task": "G"
}

Sample data: todos2 (works)

POST todos2/_doc
{
  "status": "todo",
  "task": "A"
}

POST todos2/_doc
{
  "status": "todo",
  "task": "B"
}

POST todos2/_doc
{
  "status": "todo",
  "task": "C"
}

POST todos2/_doc
{
  "status": "todo",
  "task": "C"
}

POST todos2/_doc
{
  "status": "inprogress",
  "task": "D"
}

POST todos2/_doc
{
  "status": "inprogress",
  "task": "E"
}

POST todos2/_doc
{
  "status": "inprogress",
  "task": "F"
}

POST todos2/_doc
{
  "status": "done",
  "task": "G"
}

[elasticmachine]

Pinging @elastic/kibana-app-arch

[F-PMOR]

Hi all, Do you know when this issue will be resolved ?