Java Builder apis drop old “len” methods in favour of new “length”
Rest APIs support both old “len: and new “length” forms using new ParseField class to a) provide compiler-checked consistency between Builder and Parser classes and
b) a common means of handling deprecated syntax in the DSL.
Documentation and rest specs only document the new “*length” forms
Closes#4083
Files were generated with the `thor api:generate:spec --force --verbose --crawl` command,
and based on the 0.90 branch (elasticsearch/elasticsearch@5ec4064).
Clinton Gormley
markharwood
Spencer Alger
Karel Minarik