protected void setNullText(String nullText) {
        if (nullText == null) {
            nullText = "";
        }
        this.nullText = nullText;
    }
<p>Sets the text to output when <code>null</code> found.</p>

<p><code>null</code> is accepted, but will be converted to
an empty String.</p>

@param nullText  the new text to output when null found
android/android_framework/base/src/main/java/lang3/builder/ToStringStyle.java