public static String substringAfter(String str, String separator) {
		if (isEmpty(str)) {
			return str;
		}
		if (separator == null) {
			return EMPTY;
		}
		int pos = str.indexOf(separator);
		if (pos == INDEX_NOT_FOUND) {
			return EMPTY;
		}
		return str.substring(pos + separator.length());
	}
<p>
Gets the substring after the first occurrence of a separator. The separator is not
returned.
</p>

<p>
A <code>null</code> string input will return <code>null</code>. An empty ("")
string input will return the empty string. A <code>null</code> separator will
return the empty string if the input string is not <code>null</code>.
</p>

<p>
If nothing is found, the empty string is returned.
</p>

<pre>
StringUtils.substringAfter(null, *)      = null
StringUtils.substringAfter("", *)        = ""
StringUtils.substringAfter(*, null)      = ""
StringUtils.substringAfter("abc", "a")   = "bc"
StringUtils.substringAfter("abcba", "b") = "cba"
StringUtils.substringAfter("abc", "c")   = ""
StringUtils.substringAfter("abc", "d")   = ""
StringUtils.substringAfter("abc", "")    = "abc"
</pre>
@param str the String to get a substring from, may be null
@param separator the String to search for, may be null
@return the substring after the first occurrence of the separator,
<code>null</code> if null String input
@since 2.0
spring-cloud-alibaba-starters/spring-cloud-alibaba-commons/src/main/java/com/alibaba/cloud/commons/lang/StringUtils.java