driver-core/src/main/com/mongodb/internal/HexUtils.java
public static String toHex(final byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (final byte b : bytes) {
            String s = Integer.toHexString(0xff & b);

            if (s.length() < 2) {
                sb.append("0");
            }
            sb.append(s);
        }
        return sb.toString();
    }
public static String toHex(final byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (final byte b : bytes) {
            String s = Integer.toHexString(0xff & b);

            if (s.length() < 2) {
                sb.append("0");
            }
            sb.append(s);
        }
        return sb.toString();
    }
Converts the given byte buffer to a hexadecimal string using {@link java.lang.Integer#toHexString(int)}.

@param bytes the bytes to convert to hex
@return a String containing the hex representation of the given bytes.