package converter;

public final class IntegerToHexConverter implements Converter {
  public String convert(String inputString) {
    return "hexed" + inputString;
  }
}

package converter;

public final class IntegerToHexConverter implements Converter {
  public String convert(String inputString) {
    return Long.toHexString(Long.valueOf(inputString));
  }
}

Update IntegerToHexConverter.java