版本：3.3.1
问题：批量更新或者保存方法联合主键使用了其中一个字段
日志：
Caused by: java.lang.NullPointerException
java.util.Objects.requireNonNull(Objects.java:203)
com.baomidou.mybatisplus.extension.service.impl.ServiceImpl.executeBatch(ServiceImpl.java:232)
com.baomidou.mybatisplus.extension.service.impl.ServiceImpl.executeBatch(ServiceImpl.java:252)
com.baomidou.mybatisplus.extension.service.impl.ServiceImpl.saveOrUpdateBatch(ServiceImpl.java:158)
com.baomidou.mybatisplus.extension.service.impl.ServiceImpl$$FastClassBySpringCGLIB$$76535273.invoke()
org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294)
org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
xxx.xxxx.service.wx.friend.impl.FriendServiceImpl$$EnhancerBySpringCGLIB$$514edec5.saveOrUpdateBatch()
xxx.xxxx.service.wehub.impl.WehubServiceImpl.savaFriend(WehubServiceImpl.java:264)
xxx.xxxx.service.wehub.impl.WehubServiceImpl.report_contact(WehubServiceImpl.java:216)
xxx.xxxx.service.wehub.impl.WehubServiceImpl$$FastClassBySpringCGLIB$$35e93373.invoke()
org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:684)
Friend类：
public class Friend implements Serializable {
private static final long serialVersionUID = 1L;
@TableId
private String wxId;
@TableId
private String toWxId;
}
Comment From: miemieYaho
不支持联合主键