public function getPredecessors($classFilter = null)
    {
        $returnValue = array();

        
    	foreach ($this->getCache()->getAll() as $serial => $instance) {
			
			if (($classFilter == null || $instance instanceof $classFilter)
				&& in_array($this, $instance->getSuccessors())) {
				$returnValue[] = $instance;
				break;
			}
		}
        

        return (array) $returnValue;
    }