What is wrong?

Binary encoding Since computers only operate using 0s (no voltage) and 1s (voltage), there is a need to translate human-readable data into machine-readable data. Digits, symbols and special characters have their own code (decimal number) in the Unicode table. Implement the toBinary(int) method, which converts the decimal number received as input to binary and then returns its string representation. For example, the string "CodeGym!" has the following binary representation (each character on a new line): C - 01000011 o - 01101111 d - 01100100 e - 01100101 G - 01000111 y - 01111001 m - 01101101 ! - 00100001 Requirements: 1. The toBinary(int) method needs to be implemented as outlined in the task conditions.

package en.codegym.task.jdk13.task09.task0938;

/*
Binary encoding
*/

public class Solution {

    public static void main(String[] args) {
        String string = "CodeGym!";
        char[] charArray = string.toCharArray();
        for (int i = 0; i < charArray.length; i++) {
            print(charArray[i]);
        }
    }

    private static void print(int number) {
        String result = String.format("In Unicode, the character %s is %d, but in binary it is %s", (char) number, number, toBinary(number));
        System.out.println(result);
    }

    public static String toBinary(int number) {
        int currentStepDecimalNumber = number;
        String binaryNumber = "";

        if (currentStepDecimalNumber > 0) {
            while (currentStepDecimalNumber >= 1) {
                binaryNumber = currentStepDecimalNumber % 2 + binaryNumber;
                currentStepDecimalNumber = currentStepDecimalNumber / 2;
            }
        }

        if (binaryNumber.length() % 4 == 0) {
            return binaryNumber;
        }

        return "0000".substring(binaryNumber.length() % 4) + binaryNumber;
    }
}

I am not 100% sure what the issue is because the directions are very vague. One thing that I noticed is that this method, the toBinary(), returns an empty String if the number passed to it is 0. I would think that it should return at least "0000" or "00000000". Also, it does not specify how many digits should be displayed, which is an annoying lack of information from the conditions. Should it be at least a multiple of four ? Or a multiple of eight? The above code, other than 0, outputs a multiple of four digits (four digits up to the number 15, eight digits up to 255, twelve digits above that etc). Maybe try changing it to a multiple of 8? Try those, fixing the 0 output and if that doesn't work try outputting a multiple of eight digits.