public static String defaultString(String str, String defaultStr) {
        return str == null ? defaultStr : str;
    }
<p>Returns either the passed in String, or if the String is
{@code null}, the value of {@code defaultStr}.</p>

<pre>
StringUtils.defaultString(null, "NULL")  = "NULL"
StringUtils.defaultString("", "NULL")    = ""
StringUtils.defaultString("bat", "NULL") = "bat"
</pre>

@see ObjectUtils#toString(Object,String)
@see String#valueOf(Object)
@param str  the String to check, may be null
@param defaultStr  the default String to return
 if the input is {@code null}, may be null
@return the passed in String, or the default if it was {@code null}
android/android_framework/base/src/main/java/lang3/StringUtils.java