Deadbolt for Java

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Subject requires we have a List<? extends Role> but Role is an interface, so that's not possible?

Posted by Samuil Dichev about a year ago


I've recently started implementing Deadbolt 2 into my Play Framework app. I've implemented nearly everything, including the handler / cache and etc.

It works very well if I manually add a role to a user in the database. However, I cannot edit the roles via code, because I cannot implement any kind of setter as my IDE warns me that the list of roles expects a different kind of object, so I cannot put my custom UserRole object into that list of roles on the Subject.

My User object which extends the Subject has the following fields for the Roles and Permissions:

private List<UserRole> roles;

private List<UserPermission> permissions;

These cannot be List<? extends Role> and List<? extends Permission> because of a MongoDB limitation. It needs to know how to map the embedded objects correctly, so I need to be specific.

The getters are things I've overriden from the interface and they are as the interface expects them. Example:

public List<? extends Role> getRoles() {
return roles;

They seem to work fine, since as I mentioned above, adding a role to the database manually works fine, so clearly the getters must be working properly. They are also causing no warnings. The only problem is I cannot add a UserRole or UserPermission via code. Example:

user.getRoles().add(new UserRole("Admin"));



Both can't be compiled as the IDE complains with the following
add(capture<? extends>) in List cannot be applied to (

How do I solve this, please?

Kind Regards,


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