<p>The sort order is stable, that is, if two entries have values that compare
     * as equivalent, the entry that was inserted first will be first in the built map's
     * iteration order.
<p>The sort order is stable, that is, if two entries have values that compare
     * as equivalent, the entry that was inserted first will be first in the built map's
     * iteration order. | ImmutableBiMap.java