When creating and updating transforms, it is possible for clients to provide secondary headers.
When PUT, _preview, _update is called with secondary authorization headers, those are then used or stored with the transform.
closes: https://github.com/elastic/elasticsearch/issues/86731
When a transform has a `retention_policy` it needs to be able to delete documents in the destination index.
`create_index` does not necessitate that we can delete documents from it. So, even if we create the index, we need to verify that we can delete documents given the `retention_policy` definition.
This is not a crucial bug as the transform will simply fail later. Its nicer to fail sooner.
closes https://github.com/elastic/elasticsearch/issues/85409
Removes `testenv` annotations and related code. These annotations originally let you skip x-pack snippet tests in the docs. However, that's no longer possible.
Relates to #79309, #31619
Transform writes dates as epoch millis, this does not work for historic data in some cases or is
unsupported. Dates should be written as such. With this PR transform starts writing dates in ISO
format, but as existing transform might rely on the format it provides backwards compatibility for
old jobs as well as a setting to write dates as epoch millis.
fixes#63787
If a pipeline referenced by a transform does not exist, we should not allow the transform to be created.
We do allow the pipeline existence check to be skipped with defer_validations, but if the pipeline still does not exist on `_start`, the pipeline will fail to start.
relates: #50135
