prepareAndCheck();
    public void execute() throws BuildException {        if (_pathid == null) {            throw new BuildException("pathid is required in ivy classpath");        }        try {            Path path = new Path(getProject());            getProject().addReference(_pathid, path);            for (Iterator iter = getPaths().iterator(); iter.hasNext();) {                String p = (String)iter.next();                path.createPathElement().setLocation(new File(getCache(), p));            }        } catch (Exception ex) {            throw new BuildException("impossible to build ivy path: "+ex.getMessage(), ex);        }            }