[bug] Look into camelize usage for camel case outputs

Description

See https://github.com/OpenAPITools/openapi-generator/pull/2349#discussion_r264497443

At least in the Kotlin generators, model name clean up seems to lose casing.

Example, $item would become Dollaritem rather than DollarItem.

A quick look seems to suggest that camelize causes this, and may either require an additional overload to camelize at special characters, or generators (like Kotlin) may need to reorganize logic.

openapi-generator version

master

OpenAPI declaration file content or url

Command line used for generation

Steps to reproduce

Related issues/PRs

Suggest a fix/enhancement

Have a version of camelize which capitalizes at non-alphanumeric boundaries.