Gutenberg deprecated attribute from because of changed type

Question

I develop blocks with Gutenberg for WordPress. Now I've run into a problem where I needed to change my padding attribute from type string to type array. Before I had both padding_align (to save "top" or "bottom" as alignment options) and padding (padding size). Now we want to use an array with 4 sizes (each size for each alignment).

However now I need to deal with the deprecated padding and padding_align attributes. Does anyone know how I can hook in a function in which I can updates the old padding and padding_aling into the new one.

As soon as I open the page editor the old padding gets overwritten with the default value of the new padding.

Old attributes:

attributes: {
    padding: {
        type: "string"
    },
    padding_align: {
        type: "string"
    },
}

New attributes:

attributes: {
    padding: {
        type: "array",
        default: ["disabled", "disabled", "disabled", "disabled"]
    }
}