#vulnerable code 
                             @Override
	public RegistryCenterConfiguration findConfig(String nameAndNamespace) {
		if(Strings.isNullOrEmpty(nameAndNamespace)){
			return null;
		}
		Collection<ZkCluster> zkClusters = RegistryCenterServiceImpl.ZKADDR_TO_ZKCLUSTER_MAP.values();
		for (ZkCluster zkCluster: zkClusters) {
			for(RegistryCenterConfiguration each: REGISTRY_CENTER_CONFIGURATION_MAP.get(zkCluster.getZkAddr())) {
				if (each != null && nameAndNamespace.equals(each.getNameAndNamespace())) {
					return each;
				}
			}
		}
		return null;
	} 
                            #location 8 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             @Override
	public RegistryCenterConfiguration findConfig(String nameAndNamespace) {
		if(Strings.isNullOrEmpty(nameAndNamespace)){
			return null;
		}
		Collection<ZkCluster> zkClusters = RegistryCenterServiceImpl.ZKADDR_TO_ZKCLUSTER_MAP.values();
		for (ZkCluster zkCluster: zkClusters) {
			for(RegistryCenterConfiguration each: zkCluster.getRegCenterConfList()) {
				if (each != null && nameAndNamespace.equals(each.getNameAndNamespace())) {
					return each;
				}
			}
		}
		return null;
	}