Share common attributes of extensions in the same class

[3ric-T]

When using all three extensions porvided by this plugin, configuration often looks like:

openapi {
    title = project.name
    description = project.description.toString()
    version = project.version.toString()
    format = "yaml"
}

openapi3 {
    title = project.name
    description = project.description.toString()
    version = project.version.toString()
    format = "yaml"
}

postman {
    title = project.name
    description = project.description.toString()
    version = project.version.toString()
}

As openapi and openapi3 share the same base class, above code could be factorized:

configure( listOf( openapi, openapi3 )) {
    title = project.name
    description = project.description.toString()
    version = project.version.toString()
    format = "yaml"
}

But unfortunately it cannot be applied to postman extension.

It should be useful that all those three extensions share their common attributes in the same class, in order to ease the configuration step.