@ethersproject/bignumber - is toJSON implementation correct?

[just-toby]

return { type: "BigNumber", hex: this.toHexString() };

most callsites i've seen expect the hex member to have an underscore. why remove the underscore when serializing?

i.e. why not have the implementation be the following:

return { type: "BigNumber", _hex: this.toHexString() };

[ricmoo]

The _ indicates a private member, while the serialized form assumes nothing is private.

In v6, everything uses private members, so this becomes less an issue as there is no _hex anywhere. :))