[Solved] ASP.Net Core: Fetch record from two table using EF 6 returns null

we make two table 

first one is

public class Group
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public string LegalBusinessName { get; set; }
    public string Tin { get; set; }
    public string CCN { get; set; }
    public int PartnerId { get; set; }
    public long AddressId { get; set; }
    public bool IsMIPS { get; set; }
    public int EntityTypeId { get; set; }
    public bool CalcPiScore { get; set; }
    public bool CalcQualityScore { get; set; }
    public bool CalcCpiaScore { get; set; }
    public bool IsActive { get; set; }
 
    //relation Table for one to one mappin
    public Address Address { get; set; }
}

and second table is 

public class Address
{
    public long Id { get; set; }
    public string line1 { get; set; }
    public string line2 { get; set; }
    public string line3 { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public int Zip { get; set; }
 
    public Group  Groups { get; set; }
}

one table is group and the second table is the address, define one to one mapping

builder.HasOne(a => a.Address).WithOne(b => b.Groups).HasForeignKey<Group>(f => f.AddressId).OnDelete(DeleteBehavior.NoAction);

now I make a othe class D_group

public class D_Group
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public string LegalBusinessName { get; set; }
    public string Tin { get; set; }
    public string CCN { get; set; }
    public int PartnerId { get; set; }
    public long AddressId { get; set; }
    public bool IsMIPS { get; set; }
    public int EntityTypeId { get; set; }
    public bool CalcPiScore { get; set; }
    public bool CalcQualityScore { get; set; }
    public bool CalcCpiaScore { get; set; }
    public bool IsActive { get; set; }
 
    public string line1 { get; set; }
    public string line2 { get; set; }
    public string line3 { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public int Zip { get; set; }
}

i want fetch the data we can fetch the data but address table data com null like line1, line2 etc

public async Task<Response<IList<D_Group>>> GroupList()
{
    var groups = await _context.Group.ToListAsync();
    return _mapper.Map<Response<IList<D_Group>>>(groups);
}

how can i achieve it