ensureResolved(isHaltonfailure());
    public void execute() throws BuildException {        Ivy ivy = getIvyInstance();        ensureResolved(isHaltonfailure());                _organisation = getProperty(_organisation, ivy, "ivy.organisation");        _module = getProperty(_module, ivy, "ivy.module");        if (_cache == null) {            _cache = ivy.getDefaultCache();        }        _pattern = getProperty(_pattern, ivy, "ivy.retrieve.pattern");        _conf = getProperty(_conf, ivy, "ivy.resolved.configurations");        if (_conf.equals("*")) {            _conf = getProperty(ivy, "ivy.resolved.configurations");        }                if (_organisation == null) {            throw new BuildException("no organisation provided for ivy retrieve task: It can either be set explicitely via the attribute 'organisation' or via 'ivy.organisation' property or a prior call to <resolve/>");        }        if (_module == null) {            throw new BuildException("no module name provided for ivy retrieve task: It can either be set explicitely via the attribute 'module' or via 'ivy.module' property or a prior call to <resolve/>");        }        try {            ivy.retrieve(new ModuleId(_organisation, _module), splitConfs(_conf), _cache, _pattern);        } catch (Exception ex) {            throw new BuildException("impossible to ivy retrieve: "+ex.getMessage(), ex);        }    }