### ReferenceConfig#init , at line 307
change : prifix -> prefix
<img width="746" alt="1" src="https://user-images.githubusercontent.com/6971152/35309902-a22d3ed2-00e9-11e8-9928-e394b9e3d632.png">

### by the way,  ReferenceConfig#setInterface , at line 476
it's no need to cast null to String
<img width="903" alt="2" src="https://user-images.githubusercontent.com/6971152/35309908-b09e4a92-00e9-11e8-9725-8e6ff8071370.png">

public ConsumerConfig getConsumer() {
        return consumer;
    }
    public void setConsumer(ConsumerConfig consumer) {
        this.consumer = consumer;
    }
    public String getProtocol() {
        return protocol;
    }
    public void setProtocol(String protocol) {
        this.protocol = protocol;
    }
    
    Invoker<?> getInvoker() {
        return invoker;
    }
    @Parameter(excluded = true)
    public String getUniqueServiceName() {
        StringBuilder buf = new StringBuilder();
        if (group != null && group.length() > 0) {
            buf.append(group).append("/");
        }
        buf.append(interfaceName);
        if (version != null && version.length() > 0) {
            buf.append(":").append(version);
        }
        return buf.toString();
    }
}