Enabling support for additionalProperties

[Pgarrett]

Adding support for additionalProperties containing objects. If the target DTO contains additionalProperties, then the generated DTO will contain code like:

@JsonIgnore
private val additionalProperties: MutableMap<String, ChildSchema> = mutableMapOf()

@JsonAnyGetter
fun getAdditionalProperties(): MutableMap<String, ChildSchema> {
    return additionalProperties
}

@JsonAnySetter
fun addAdditionalProperty(name: String, value: ChildSchema) {
    additionalProperties[name] = value
}

Where ChildSchema is the nested object represented in the additionalProperties.

[arcuri82]

this kind of function should be in a utility class, as can be re-used throughout the codebase. for example, before writing something like this, should check what available in org.evomaster.core.utils... there, you can find StringUtils.capitalization() :)

[Pgarrett]

Close enough! The capitalization function lowercases the rest of the word, I just want the first char to be capitalized. I'll move the function to StringUtils though.