用jarslink做module隔离时,dubbo调用会抛ClassNotFoundException.经查是ClassLoader不一致.

```
    public static Class<?> getReturnType(Invocation invocation) {
        try {
            if (invocation != null && invocation.getInvoker() != null
                    && invocation.getInvoker().getUrl() != null
                    && !invocation.getMethodName().startsWith("$")) {
                String service = invocation.getInvoker().getUrl().getServiceInterface();
                if (service != null && service.length() > 0) {
                    Class<?> cls = ReflectUtils.forName(service);
                    Method method = cls.getMethod(invocation.getMethodName(), invocation.getParameterTypes());
                    if (method.getReturnType() == void.class) {
                        return null;
                    }
                    return method.getReturnType();
                }
            }
        } catch (Throwable t) {
            logger.warn(t.getMessage(), t);
        }
        return null;
    }
```
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package org.apache.dubbo.rpc.support;