Fix compilation error from last commit.
Fix PMD warning: don't reassign method parameters.
[TEST] Make sure that there are no relocating shards before taking snapshot

Temporary workaround for #5531
[TEST] Added extra test for multi fields with default `include_in_all` settings, in which only the main field should end up in the `_all` field.
add uppercase token filter

closes #5539
Fix for zero-sized content throwing off toChannelBuffer(). Also
short-circuit writeTo(..) accordingly to avoid unnecessary work.

Fixes #5543
Capture and set start time in Delete By Query operations

This is important for queries/filters that use `now` in date based queries/filters

Closes #5540
Assorted fixes for bugs in the PagedBytesReference tests, plus a typo
where the wrong variable was used for a calculation.

Closes #5549
[DOCS] fixed typo

Closes #5272
[TEST] Increase logging on MinDocCountTests.
Convert TermQuery to PrefixQuery if PHRASE_PREFIX is set

We miss to add a single term to a prefix query if the query in only a
single term.

Closes #5551
[DOCS] Clarify nested type documentation
[TEST] Moved wipe* methods, randomIndexTemplate & ensureEstimatedStats from ElasticsearchIntegrationTest to TestCluster

This is the first to make it possible to have a different impl of TestCluster (e.g. based on an external cluster) that has the same methods but a different impl for them (e.g. it might use the REST API to do the same instead of the Java API)

Closes #5542
[TEST] removed leftover ElasticsearchIntegrationTest#randomIndexTemplate

used cluster().randomIndexTemplate instead
Remove deprecated gateways

Closes #5422
Fixes a bug when the field has been configured with eager fielddata loading, the fielddata is not being loaded.

Closes #5557
Fixed space in licence header.
Now really fix eager fielddata loading.

Relates to #5557
[DOCS] `_type` instead of Type Field
[TEST] Made ttl test more predictable
* Only run the test with one node, to make sure only a single purger thread is running.
* Instead of generating the _timestamp upon indexing in ES, define the _timestamp in the documents.
* Verify the responses from the index requests.