@Override
@Query(value = "select u from User u where u.region in :#{principal.region}")
Page<User> findAll(Pageable var1);

@ManyToMany( mappedBy = "users")
private List<Region> region = new ArrayList<>();

@ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE})
@JoinTable(name = "region_users", joinColumns = @JoinColumn(name = "region_id", referencedColumnName= "id"),
        inverseJoinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id")
)
private List<User> users = new ArrayList<>();

private List<Region> region;

public UserPrincipal(Long id, String username, String password,
                     Collection<? extends GrantedAuthority> authorities, Role role, List<Region> region) {
    this.id = id;
    this.username = username;
    this.password = password;
    this.authorities = authorities;
    this.role = role;
    this.region = region;
}

public List<Region> getRegion() { return this.region; }