public StrBuilder setNullText(String nullText) {
        if (nullText != null && nullText.isEmpty()) {
            nullText = null;
        }
        this.nullText = nullText;
        return this;
    }
public StrBuilder setNullText ( String nullText ) { if ( nullText != null && nullText . isEmpty ( ) ) { nullText = null ; } this . nullText = nullText ; return this ; }
Sets the text to be appended when null is added.

@param nullText  the null text, null means no append
@return this, to enable chaining