错误信息：

feign.codec.DecodeException: Type definition error: [simple type, class org.springframework.security.core.GrantedAuthority]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.springframework.security.core.GrantedAuthority` (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information

 at [Source: (PushbackInputStream); line: 1, column: 954] (through reference chain: com.gaojingsi.record.common.domain.vo.SimpleResponse["data"]->com.gaojingsi.record.common.domain.SysUser["authorities"]->java.util.ArrayList[2])

我是在授权服务器用Feign去获取用户服务里的UserDetails实体，把fallback去掉以后，看到了错误，如上。

仿佛原因是我的UserDetails里的权限字段（public Collection<? extends GrantedAuthority> getAuthorities()
）没法反序列化到实体里。想这个情况应该怎么办呢？好像很复杂。