Bug 63223 Use null to clear message text instead of empty string
I200405200800 StatusLine in jface uses setMessage("") to clear the text while the documentation says you should uset setMessage(null) to clear the text. The code path is slightly different for "" versus null, but using null makes the intent of the caller clearer.
bundles/org.eclipse.jface/src/org/eclipse/jface/action/StatusLine.java
}
    /**
     * @see IProgressMonitor#internalWorked(double)
     */
    public void internalWorked(double work) {
        if (!fProgressIsVisible) {
            if (System.currentTimeMillis() - fStartTime > DELAY_PROGRESS)
                showProgress();
        }
        if (fProgressBar != null) {
            fProgressBar.worked(work);
        }
    }
    /**
     * Returns true if the user does some UI action to cancel this operation.
     * (like hitting the Cancel button on the progress dialog).
     * The long running operation typically polls isCanceled().
     */
    public boolean isCanceled() {
        return fIsCanceled;
    }
    /**
     * Returns <code>true</true> if the ProgressIndication provides UI for canceling
     * a long running operation.
     */
    public boolean isCancelEnabled() {
        return fCancelEnabled;
    }
    /**
     * Sets the cancel status. This method is usually called with the