=== tests/cases/compiler/jsDocOptionality.js ===
function MyClass() {
>MyClass : typeof MyClass

  this.prop = null;
>this.prop = null : null
>this.prop : any
>this : this
>prop : any
>null : null
}
/**
 * @param  {string} required
 * @param  {string} [notRequired]
 * @returns {MyClass}
 */
MyClass.prototype.optionalParam = function(required, notRequired) {
>MyClass.prototype.optionalParam = function(required, notRequired) {    return this;} : (required: string, notRequired?: string) => MyClass
>MyClass.prototype.optionalParam : any
>MyClass.prototype : any
>MyClass : typeof MyClass
>prototype : any
>optionalParam : any
>function(required, notRequired) {    return this;} : (required: string, notRequired?: string) => MyClass
>required : string
>notRequired : string

    return this;
>this : this

};
let pInst = new MyClass();
>pInst : MyClass
>new MyClass() : MyClass
>MyClass : typeof MyClass

let c1 = pInst.optionalParam('hello')
>c1 : MyClass
>pInst.optionalParam('hello') : MyClass
>pInst.optionalParam : (required: string, notRequired?: string) => MyClass
>pInst : MyClass
>optionalParam : (required: string, notRequired?: string) => MyClass
>'hello' : "hello"

let c2 = pInst.optionalParam('hello', null)
>c2 : MyClass
>pInst.optionalParam('hello', null) : MyClass
>pInst.optionalParam : (required: string, notRequired?: string) => MyClass
>pInst : MyClass
>optionalParam : (required: string, notRequired?: string) => MyClass
>'hello' : "hello"
>null : null