/// <summary>
/// Add an `allOf` keyword to the schema.
/// </summary>
public static JsonSchema AllOf(this JsonSchema schema, params JsonSchema[] definitions)
{
var keyword = schema.OfType <AllOfKeyword>().FirstOrDefault();
if (keyword == null)
{
keyword = new AllOfKeyword();
schema.Add(keyword);
}
keyword.AddRange(definitions);
return(schema);
}