The TokenCount in the FieldType seems to be misspelled.

[oni7uka]

Hi, guys
Datatype.TokenCount is mapped to tokencount, resulting in elasticsearch mapper_parsing_exception:

"type":"mapper_parsing_exception","reason":"no handler for type [tokencount] declared on field [length]"

The correct mapping should be token_count

[sothawo]

Note: FieldType values are mapped by lowercasing their name. We should add the names explicitly to the enum to prevent such mistakes in the future.

[sothawo]

added in main and backported to 4.3.x and 4.2.x.