Is behavior of available task on empty file attribute as expected?

[Kottmann, Renzo (Finanzen) 443-1]

Hi,

My very first question after all the years using it (even before Maven came to 
life):

Using Apache Ant(TM) version 1.10.15

    <!-- expected? An empty  string should not lead to the statement the file 
would exist?!? -->
    <available file="" property="file.prop.empty" />
<!-- gives: empty file.present=true  -->
    <echo message="empty file.present=${file.prop.empty}" />
  
  <!-- expected -->
    <available file="${basedir}" property="file.exist" />
    <echo message="${basedir} present=${file.exist}" /> 

Is this a bug or feature I do not know the reason for?

Thx in advance.

Ciao,

renzo