in generate/property.go [174:184]
func (p Property) HasValidType() bool {
invalid := p.ItemType == "" &&
p.PrimitiveType == "" &&
p.PrimitiveItemType == "" &&
p.Type == "" &&
len(p.ItemTypes) == 0 &&
len(p.PrimitiveTypes) == 0 &&
len(p.PrimitiveItemTypes) == 0 &&
len(p.Types) == 0
return !invalid
}