我得到的错误日志（部分错误）：
mClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)`2019-01-03 11:48:45.070 28064-28064/com.example.xandi.whib E/AndroidRuntime: at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$200(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.serialize(com.google.firebase:firebase-database@@16.0.5:663)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.serialize(com.google.firebase:firebase-database@@16.0.5:167)
at …