Currently dubbo support java6, java7 and java8.

All unit test pass in java9, we should consider add official support for java9 and even java10.
Currently travis support java9. java10 is in progress (https://github.com/travis-ci/travis-ci/issues/9368)

As discussed in mail list, the first step is to add java9 in travis ci.
c = Short.class;
        }
        if (c == o.getClass())
            return true;
        return c.isInstance(o);
    }
    /**
     * is compatible.
     *
     * @param cs class array.
     * @param os object array.
     * @return compatible or not.
     */
    public static boolean isCompatible(Class<?>[] cs, Object[] os) {
        int len = cs.length;
        if (len != os.length) return false;
        if (len == 0) return true;
        for (int i = 0; i < len; i++)
            if (!isCompatible(cs[i], os[i])) return false;
        return true;
    }
    public static String getCodeBase(Class<?> cls) {
        if (cls == null)
            return null;
        ProtectionDomain domain = cls.getProtectionDomain();
        if (domain == null)
            return null;
        CodeSource source = domain.getCodeSource();
        if (source == null)
            return null;