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.
for (int i = 0; i < parameterTypes.length; i++)
            ret.append(getDesc(parameterTypes[i]));
        ret.append(')').append(getDesc(m.getReturnType()));
        return ret.toString();
    }
    /**
     * name to desc.
     * java.util.Map[][] => "[[Ljava/util/Map;"
     *
     * @param name name.
     * @return desc.
     */
    public static String name2desc(String name) {
        StringBuilder sb = new StringBuilder();
        int c = 0, index = name.indexOf('[');
        if (index > 0) {
            c = (name.length() - index) / 2;
            name = name.substring(0, index);
        }
        while (c-- > 0) sb.append("[");
        if ("void".equals(name)) sb.append(JVM_VOID);
        else if ("boolean".equals(name)) sb.append(JVM_BOOLEAN);
        else if ("byte".equals(name)) sb.append(JVM_BYTE);
        else if ("char".equals(name)) sb.append(JVM_CHAR);
        else if ("double".equals(name)) sb.append(JVM_DOUBLE);
        else if ("float".equals(name)) sb.append(JVM_FLOAT);
        else if ("int".equals(name)) sb.append(JVM_INT);
        else if ("long".equals(name)) sb.append(JVM_LONG);
        else if ("short".equals(name)) sb.append(JVM_SHORT);
        else sb.append('L').append(name.replace('.', '/')).append(';');