What is the reason of default bias initialization in Conv2d/ Linear?

def reset_parameters(self):
        init.kaiming_uniform_(self.weight, a=math.sqrt(5))
        if self.bias is not None:
            fan_in, _ = init._calculate_fan_in_and_fan_out(self.weight)
            bound = 1 / math.sqrt(fan_in)
            init.uniform_(self.bias, -bound, bound)

I am not sure if someone else has asked the question, may I know why is the bias in Conv2d is not initialized as 0 but initialized using uniform_(-bound, bound). Can someone share the knowledge on it? Thanks!