- [x] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate.
- [x] I have checked the [FAQ](https://github.com/apache/dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: 2.7.4
* Operating System version: Darwin Kernel Version 18.7.0
* Java version: 1.8.0_181-b13)

### Steps to reproduce this issue

1. invoke `StringUtils.split("d,1,2,4", 'a')`
2. invoke `"d,1,2,4".split("a")`

Pls. provide [GitHub address] to reproduce this issue.

### Expected Result

`StringUtils.split("d,1,2,4", 'a')` should return `["d,1,2,4"]` just like `"d,1,2,4".split("a")`.

### Actual Result

empty array.

* @return is empty.
     */
    public static boolean isEmpty(String str) {
        return str == null || str.isEmpty();
    }
    /**
     * <p>Checks if the strings contain empty or null elements. <p/>
     *
     * <pre>
     * StringUtils.isNoneEmpty(null)            = false
     * StringUtils.isNoneEmpty("")              = false
     * StringUtils.isNoneEmpty(" ")             = true
     * StringUtils.isNoneEmpty("abc")           = true
     * StringUtils.isNoneEmpty("abc", "def")    = true
     * StringUtils.isNoneEmpty("abc", null)     = false
     * StringUtils.isNoneEmpty("abc", "")       = false
     * StringUtils.isNoneEmpty("abc", " ")      = true
     * </pre>
     *
     * @param ss the strings to check
     * @return {@code true} if all strings are not empty or null
     */
    public static boolean isNoneEmpty(final String... ss) {
        if (ArrayUtils.isEmpty(ss)) {
            return false;
        }
        for (final String s : ss) {
            if (isEmpty(s)) {
                return false;
            }