Dubbo 和 JDK 版本不匹配

Maven项目，使用Dubbo 2.8.4，启动报错：

POM.XML依赖如下：

com.alibaba
dubbo 
2.8.4

Eclipse报错如下：

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.qhgrain.api.iUnitService': Instantiation of bean failed; nested exception is java.lang.ExceptionInInitializerError

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1101)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1046)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:755)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
at org.springframework.context.support.FileSystemXmlApplicationContext.(FileSystemXmlApplicationContext.java:140)
at org.springframework.context.support.FileSystemXmlApplicationContext.(FileSystemXmlApplicationContext.java:84)
at com.ycf.privilege.test.TestMain.main(TestMain.java:9)
Caused by: java.lang.ExceptionInInitializerError
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:147)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:89)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1094)
... 13 more
Caused by: java.lang.IllegalStateException: fail to create adaptive instance: java.lang.IllegalStateException: Can not create adaptive extenstion interface com.alibaba.dubbo.rpc.Protocol, cause: fail to create adaptive instance: java.lang.NoSuchMethodError: java.util.concurrent.ConcurrentHashMap.keySet()Ljava/util/concurrent/ConcurrentHashMap$KeySetView;
at com.alibaba.dubbo.common.extension.ExtensionLoader.getAdaptiveExtension(ExtensionLoader.java:459)
at com.alibaba.dubbo.config.ServiceConfig.(ServiceConfig.java:62)
... 20 more
Caused by: java.lang.IllegalStateException: Can not create adaptive extenstion interface com.alibaba.dubbo.rpc.Protocol, cause: fail to create adaptive instance: java.lang.NoSuchMethodError: java.util.concurrent.ConcurrentHashMap.keySet()Ljava/util/concurrent/ConcurrentHashMap$KeySetView;
at com.alibaba.dubbo.common.extension.ExtensionLoader.createAdaptiveExtension(ExtensionLoader.java:723)
at com.alibaba.dubbo.common.extension.ExtensionLoader.getAdaptiveExtension(ExtensionLoader.java:455)
... 21 more
Caused by: java.lang.IllegalStateException: fail to create adaptive instance: java.lang.NoSuchMethodError: java.util.concurrent.ConcurrentHashMap.keySet()Ljava/util/concurrent/ConcurrentHashMap$KeySetView;
at com.alibaba.dubbo.common.extension.ExtensionLoader.getAdaptiveExtension(ExtensionLoader.java:459)
at com.alibaba.dubbo.common.extension.ExtensionLoader.createAdaptiveExtensionClass(ExtensionLoader.java:738)
at com.alibaba.dubbo.common.extension.ExtensionLoader.getAdaptiveExtensionClass(ExtensionLoader.java:732)
at com.alibaba.dubbo.common.extension.ExtensionLoader.createAdaptiveExtension(ExtensionLoader.java:721)
... 22 more
Caused by: java.lang.NoSuchMethodError: java.util.concurrent.ConcurrentHashMap.keySet()Ljava/util/concurrent/ConcurrentHashMap$KeySetView;
at com.alibaba.dubbo.common.utils.ConcurrentHashSet.iterator(ConcurrentHashSet.java:48)
at com.alibaba.dubbo.config.spring.extension.SpringExtensionFactory.getExtension(SpringExtensionFactory.java:44)
at com.alibaba.dubbo.common.extension.factory.AdaptiveExtensionFactory.getExtension(AdaptiveExtensionFactory.java:47)
at com.alibaba.dubbo.common.extension.ExtensionLoader.injectExtension(ExtensionLoader.java:533)
at com.alibaba.dubbo.common.extension.ExtensionLoader.createAdaptiveExtension(ExtensionLoader.java:721)
at com.alibaba.dubbo.common.extension.ExtensionLoader.getAdaptiveExtension(ExtensionLoader.java:455)

关键在于红字部分：java.util.concurrent.ConcurrentHashMap.keySet()  需要JDK8或以上版本，更换JDK8或者使用较低版本的Dubbo