title: Why does setProperty in Java return Object?
body: <p>The Properies class in Java SE 6 has a method called <code>setProperty(String key, String value)</code>, which returns an <code>Object</code>. Furthermore, the previous <code>Object</code> stored for this key, or <code>NULL</code> if none exists.
  Since <code>setProperty(String key, String value)</code> can only take a <code>String</code> as value, why doesn't that method return a <code>String</code>?</p>