// Digester digester = DigesterLoader.createDigester(sipXmlRules);
EntityResolver entityResolver = new SipEntityResolver();
digester.setValidating(false);
digester.setClassLoader(SipParser.class.getClassLoader());
digester.setEntityResolver(entityResolver);
digester.resolveEntity(null, null);
digester.setValidating(false);
SipDeploymentDescriptorRuleSet ruleSet = new SipDeploymentDescriptorRuleSet();
ruleSet.addRuleInstances(digester);