Please, is there a way to hide his code? No spoilers :)

First: I have no power to reinstate eligibility! Sorry for that.
Then: 92 guys passed the Java kata. I don't know why test 8 works locally and sometimes at CW and some others no. Do you print the input and your output to see what happens?

Done. Thanks for the kata!

For some reason test cases 7 and 8 fail for me, even though my solution works locally. Oddly, test case 8 works on some attempts but not others.
I had to forfeit eligibility for the points to see the cases but haven't changed my solution since. If it is correct, is there a way to reinstate eligibility?

private static final String DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

public static String converter(double n, int decimals, double base) {
    if (n == 0) return "0";

    boolean isNeg = n < 0;
    n = Math.abs(n);

    StringBuilder sb = new StringBuilder();
    for (int exponent = (int) (Math.log(n) / Math.log(base)); exponent > -decimals - 1; exponent--) {
        if (exponent == -1) {
            sb.append(".");
        }
        sb.append(DIGITS.charAt((int) (n / Math.pow(base, exponent))));
        n %= Math.pow(base, exponent);
    }
    return (isNeg ? "-" : "") + sb.toString();
}

Post under the translator comment, please :)!