Why does Closure compiler rename properties of an extern type?

Question

I put this in an externs file:

/** @typedef {{english: string, spanish: string}} */
var SpanishNoun;

Then I have javascript:

Answer 1

typedefs don't participate in the renaming calculation

This type definition will:

/** @interface */
function SpanishNoun() {}
/** @type {string} */
SpanishNoun.prototype.english;
/** @type {string} */
SpanishNoun.prototype.spanish;