Android : Reference in R.java not final

When generating the reference for a stylable attribute there seems to be something going wrong in the generation of the R.java file.

One would expect the declaration of the field to be final but it is not. How come?

res/values/attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="MyTextView">
        <attr name="typeface" format="string"/>
    </declare-styleable>
</resources>

gen/com.example/R.java

    /**
      <p>This symbol is the offset where the {@link com.example.R.attr#typeface}
      attribute's value can be found in the {@link #MyTextView} array.
      <p>Must be a string value, using '\\;' to escape characters such as '\\n' or '\\uxxxx' for a unicode character.
      <p>This may also be a reference to a resource (in the form "<code>@[<i>package</i>: <i>type</i>:<i>name</i></code>") or theme attribute (in the form "<code>?[<i>package</i>: [<i>type</i>:]<i>name</i></code>") containing a value of this type. 
       @attr name com.example:typeface
    */
    public static int MyTextView_typeface = 0;