addFeedback("Failed to extract \'" + expression + "\' from: " + root, e);
            }

            return null;
        }
    }

    /**
     * Wraps another value source and intercepts interpolated expressions, checking for problems.
     *
     */
    static class ProblemDetectingValueSource implements ValueSource {

        private final ValueSource valueSource;

* Assumptions: What is Offline?

  For the purposes of determining the areas sensitive to offline status,
  it is definitely useful to define what the offline state really means.

  [[1]] This is obvious, but the network/internet is unavailable.

  [[2]] Localhost (127.0.0.1) may also be unavailable if the whole
        network stack is offline.

  [[3]] "Remote" repositories referenced using the file:// protocol may

school, if any, to sign a "copyright disclaimer" for the program, if
necessary. Here is a sample; alter the names:

    Yoyodyne, Inc., hereby disclaims all copyright interest in the
    program `Gnomovision' (which makes passes at compilers) written by
    James Hacker.

    signature of Ty Coon, 1 April 1989
    Ty Coon, President of Vice