public static <T extends CharSequence> T defaultIfBlank(T str, T defaultStr) {
        return StringUtils.isBlank(str) ? defaultStr : str;
    }
<p>Returns either the passed in CharSequence, or if the CharSequence is
whitespace, empty ("") or {@code null}, the value of {@code defaultStr}.</p>

<pre>
StringUtils.defaultIfBlank(null, "NULL")  = "NULL"
StringUtils.defaultIfBlank("", "NULL")    = "NULL"
StringUtils.defaultIfBlank(" ", "NULL")   = "NULL"
StringUtils.defaultIfBlank("bat", "NULL") = "bat"
StringUtils.defaultIfBlank("", null)      = null
</pre>
@param <T> the specific kind of CharSequence
@param str the CharSequence to check, may be null
@param defaultStr  the default CharSequence to return
 if the input is whitespace, empty ("") or {@code null}, may be null
@return the passed in CharSequence, or the default
@see StringUtils#defaultString(String, String)
android/android_framework/base/src/main/java/lang3/StringUtils.java