Add Kotlin reflection support to `ModelOptionsUtils`

[sdeleuze]

As documented via #1666, schema generation from Kotlin classes currently requires using non idiomatic code like data class Foo(@get:JsonProperty(required = true, value = "output") val bar: String) while the required information can be inferred from Kotlin null-safety and the value inferred from Kotlin reflection.

A related com.github.victools.jsonschema.generator.Module instance could be implemented and created when KotlinDetector.isKotlinReflectPresent() == true to provide those information automatically here.

That would allow to perform schema generation with just data class Foo(val bar: String).

[devcrocod]

Hi,

I have some question regarding this issue, please clarify follow points:

• In a data class like data class Foo(val bar: String, val baz: String?), should the property baz be not marked as required in the generated JSON schema because it's nullable, even though it doesn't have a default value? Or should it only be considered not required if it has a default value, like in data class Foo(val bar: String, val baz: String? = null)?

• Also about properties with default values: How should the module handle non-nullable properties with default values, such as in data class Foo(val bar: String, val baz: Int = 10)?

• Should the same logic be handled for functions?