jodd-core/src/main/java/jodd/util/StringUtil.java
public static String maxCommonPrefix(final String one, final String two) {
        final int minLength = Math.min(one.length(), two.length());

        final StringBuilder sb = new StringBuilder(minLength);
        for (int pos = 0; pos < minLength; pos++) {
            final char currentChar = one.charAt(pos);
            if (currentChar != two.charAt(pos)) {
                break;
            }
            sb.append(currentChar);
        }

		return sb.toString();
	}
public static String maxCommonPrefix(final String one, final String two) {
        final int minLength = Math.min(one.length(), two.length());

        final StringBuilder sb = new StringBuilder(minLength);
        for (int pos = 0; pos < minLength; pos++) {
            final char currentChar = one.charAt(pos);
            if (currentChar != two.charAt(pos)) {
                break;
            }
            sb.append(currentChar);
        }

		return sb.toString();
	}
Returns max common prefix of two strings.