* [feat] Intro GeneratorMetadata (stability index)
GeneratorMetadata offers an immutable object created via Builder pattern
which allows generators to explicitly define their stability (stable,
beta, experimental, deprecated) as well as a message to be shown during
generation.
This is a step toward:
* Fleshing out the "Core" artifact (#845)
* Providing a place to encapsulate feature-oriented metadata (#840)
* Providing a means to communicate end of life scheduling (#116)
This new structure, specifically the Stability property, allows us to
offer future enhancements such as allowing users to filter down to only
"Stable" generators via CLI, and eventually any compat table (see #503).
* Mark deprecated generators as deprecated in-code
* Re-export docs/generators.md
* new module: openapi-generator-core
* templating engine adapters to support extension (currently only Handlebars)
* new `-e` templating engine CLI option
* adapt Generator to process Template with the passed TemplatingEngineAdpater
* add a MustacheEngineAdapter to the codegen in the unit tests
* force default MustacheEngineAdapter
* copy new core module in the root Dockerfile
* add processTemplatingEngine to CodegenConfig, to be overriden by Codegen classes if needed
* support multiple file extensions per templating engine adapter
* Extends handlebars experimental adapter with explicit contextual resolvers (e.g. map processing)
* Add new openapi-generator-core/pom.xml to release_version_update.sh
* A detailed message will be logged on missing handlebars helper
* Adds README documentation around template default and beta options
* Moves mustache package under new templating package
* Include built-in handlebars helpers which require explicit registration, and custom `startsWith` helper.
