Relevant code:

double y = Double.NaN
while (Double.isNaN(y) && someOtherCondition) {
    ...
    y = Double.parseDouble(...);
    ...
}

Reported:

FL_FLOATS_AS_LOOP_COUNTERS: Do not use floating-point variables as loop counters

Using floating-point variables should not be used as loop counters, as they are not precise, which may result in incorrect loops. A loop counter is a variable that is changed with each iteration and controls when the loop should terminate. It is decreased or increased by a fixed amount each iteration.

See rule NUM09-J.

However, there is no fixed increment, so I think it does not apply here.

Bytecode:
FollowTarget.zip