Migrate from Trove to Hppc.
Also clear handlesText
Changed nested filter example to use an inner bool filter instead of a bool query, to demonstrate the usage of a filter rather than a query.
[DOCS] Updated ICU-Plugin docs from the repo README
[DOCS] Removed enable_position_increments in stop filter
[DOCS] Fixed typo
[DOCS] Changed capitalization of operator in rescore query
Warn users with IAE if pos_inc is disabled in 'stop' filter
fix typo - s/Deprected/Deprecated
Add simple test for delete by field query
Disable ConcurrentDynamicTemplateTests for now
Changed documentation to use getter notation

Updated some java documentation to reflect the use of getters instead of calling methods based on field names.

Relates to #2657
use the already used constant for match no filter
Better logic ignoring filters when parsing
When parsing a filter, we effectively have a case where we need to ignore a filter. For example, when an "and" filter has no elements. Ignoring a filter is different compared to matching on all or matching on none, because an and filter with no elements should simply be ignored in the context of a bool filter for example, regardless if its used within a must or a must_not filter.

We should be consistent in our codebase when handling these use case. See also #3809

closes #3838
[DOCS] Added pages explaining lucene query parser syntax and regular expression syntax
Rejecting invalid fields inside of completion field

Only valid fields (input, output, weight and payload) are now allowed inside a completion field.
This makes sure that typos like "inputs" are caught on indexing.
Improve exception handling for river startup

Due to a change in 0.90 some exceptions may show up when starting a river,
even though this is not a problem as the shard has not been initialized
yet and a retry is scheduled.
Remove @Required annotation

The @Required annotation is used for documentation purposes only anyway.
Add FieldMappers before adding Mappers (used for parsing) and while holding the relevant's ObjectMapper mutex

Adding the mappers first could cause the wrong FieldMappers to be used during object parsing

Also:
Removed MergeContext.newFieldMappers, MergeContext.newObjectMappers and relatives as they are not used anymore.
Similarly removed MergeContext.addFieldDataChange & fieldMapperChanges as they were not used.

Closes #3844