Immutable.Map hashCode collision when swapping the boolean values in an object

[brianshih1]

What happened

I created two immutable.Map instances as follows:

const first = immutable.Map({ foo: true, valid: false })
const second = immutable.Map({ foo: false, valid: true })

These two objects have the same keys but swapped boolean values.

I noticed that they have the same hashCode. I would've assumed the hashCode is different since all I did is swap the boolean values for the two keys. This also seems to happen for these specific combination of words since the hashCode is different if I swap valid for bar.

How to reproduce

Create the two immutable.Map instances and look at the hashCode

[jdeniau]

hashCode might have a Collision according to the documentation

The "bug" was already present in 3.8.2 : https://runkit.com/jdeniau/621fd7b26f5ba1000804a031

To be honest, the hashCode implementation is pretty obscure to me and I really do not know how to fix that without possible side effects.

[Skywalker13]

Use equals() instead of the hashCode if you want to compare both immutable objects.