### 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">

this.interfaceClass = interfaceClass;
        setInterface(interfaceClass == null ? (String) null : interfaceClass.getName());
    }
    public void setInterface(String interfaceName) {
        this.interfaceName = interfaceName;
        if (id == null || id.length() == 0) {
            id = interfaceName;
        }
    }
    public String getClient() {
        return client;
    }
    public void setClient(String client) {
        checkName("client", client);
        this.client = client;
    }
    @Parameter(excluded = true)
    public String getUrl() {
        return url;
    }
    public void setUrl(String url) {
        this.url = url;
    }
    public List<MethodConfig> getMethods() {
        return methods;
    }
    @SuppressWarnings("unchecked")
    public void setMethods(List<? extends MethodConfig> methods) {
        this.methods = (List<MethodConfig>) methods;
    }