The @Required
annotation tells Realm to apply controls to reject null values.
When the @Required annotation is added to a RealmList of primitive types, example:
RealmList <String>, RealmList <byte []>, RealmList <Boolean>, RealmList <Byte>,
RealmList <Short>, RealmList <Integer>, RealmList <Long>, RealmList
<Float>, RealmList <Double >, RealmList <Date>
, this can not contain null values.
Review the documentation related to the @Required notation
You should check in your classes if you are adding this annotation, regularly the problem is to define it in some class
@Required
private MyClass myclase;