R$-2\mathrm{.}5$ Assume that we change the CreditCard class $($see Code Fragment $1\mathrm{.}5)$ so that

instance variable balance has private visibility. Why is the following implementation

of the PredatoryCreditCard.charge method flawed?

public boolean charge$($double price$)\{$ boolean isSuccess $=$ super.charge$($price$)$;

if $(!$isSuccess$)$

super.charge$(5)$; $//$ the penalty

return isSuccess;

$\}$