title: Typescript array of key value pairs declaration
body: <p>Confused about the following declaration:</p>
  
  <pre><code>constructor(controls: {[key: string]: AbstractControl}, optionals?: {[key: string]: boolean}, validator?: ValidatorFn, asyncValidator?: AsyncValidatorFn)
  </code></pre>
  
  <p>What is the type of the controls (first parameter)?
  Is it an object which is an array of key value pairs where key is string and value is AbstractControl? Thanks!</p>