jodd-core/src/main/java/jodd/util/StringUtil.java
public static String trimDown(String string) {
		string = string.trim();
		if (string.length() == 0) {
			string = null;
		}
		return string;
	}
public static String trimDown(String string) {
		string = string.trim();
		if (string.length() == 0) {
			string = null;
		}
		return string;
	}
Trims string and sets to <code>null</code> if trimmed string is empty.