This change also removes the reference to the difference bewteen full name and index name.
They are always the same since 2.x and `name` does not refer anymore to `author.name` automatically.
A simple pattern must be used instead.
Remove redundant code that checks the field name twice.
This new API allows to get the mapping for a specific set of fields rather than get the whole index mapping and traverse it.
The fields to be retrieved can be specified by their full path, index name and field name and will be resolved in this order.
In case multiple field match, the first one will be returned.
Since we are now generating the output (rather then fall back to the stored mapping), you can specify `include_defaults`=true on the request to have default values returned.
Closes#3941
Jim Ferenczi
Nik Everett
Adrien Grand
Ryan Ernst
Clinton Gormley
Boaz Leskes
Andrew Raines