public void addAll(Collection<Permission> perms) {
        if (perms != null && !perms.isEmpty()) {
            Set<Permission> permissions = getPermissions();
            if (permissions == null) {
                permissions = new LinkedHashSet<Permission>(perms.size());
                setPermissions(permissions);
            }
            permissions.addAll(perms);
        }
    }
A simple representation of a security role that has a name and a collection of permissions.  This object can be
used internally by Realms to maintain authorization state.

@since 0.2
core/src/main/java/org/apache/shiro/authz/SimpleRole.java