Support for collections

[Senthil-Sivanath]

Exposing additional methods for collections would be helpful, for example in the Type class at present we have setter for name, properties and it would be useful if we can have addItem(key, property);

I tried adding a manual method inside Type class but it wasn't able to accept a object built out of builder lib. Found it strange.

export class Type {
    
    name: string;
    properties: Map<String, Property> = new Map<String, Property>();

export class Property {
    name: string;
}