Entity Framework The migration of cascade delete is always true, even WillCascadeOnDelete (false) in the configuration

Why is the relationship with WillCascadeOnDelete (false) defined in the configuration always true in the generated migration?

Here is the configuration code

 public class PartySuppliesConfiguration:EntityTypeConfiguration<PartySupplies>
{
    public PartySuppliesConfiguration()
    {
        HasKey(x => x.Id);
        HasRequired(x=>x.Supplier).WithMany().HasForeignKey(x=>x.SupplierId).WillCascadeOnDelete(false);
        HasRequired(x => x.Product).WithMany().HasForeignKey(x => x.ProductId).WillCascadeOnDelete(false);
        HasRequired(x => x.Currency).WithMany().HasForeignKey(x => x.CurrencyId).WillCascadeOnDelete(false);
        HasRequired(x => x.CreatedUser).WithMany().HasForeignKey(x => x.CreatedUserId).WillCascadeOnDelete(false);
        Property(x => x.UnitPrice).HasColumnType("Money");
    }
}

and here is the generated migration

 public override void Up()
    {
        CreateTable(
            "PartySupplies",
            c => new
                {
                    Id = c.Int(nullable: false, identity: true),
                    SupplierId = c.Int(nullable: false),
                    ProductId = c.Int(nullable: false),
                    UnitPrice = c.Decimal(nullable: false, precision: 18, scale: 2),
                    CurrencyId = c.Int(nullable: false),
                    FromDate = c.DateTime(nullable: false),
                    ThruDate = c.DateTime(),
                    CreatedUserId = c.Int(nullable: false),
                })
            .PrimaryKey(t => t.Id)
            .ForeignKey("Parties", t => t.SupplierId, cascadeDelete: true)
            .ForeignKey("Products", t => t.ProductId, cascadeDelete: true)
            .ForeignKey("Curencies", t => t.CurrencyId, cascadeDelete: true)
            .ForeignKey("Users", t => t.CreatedUserId, cascadeDelete: true)
            .Index(t => t.SupplierId)
            .Index(t => t.ProductId)
            .Index(t => t.CurrencyId)
            .Index(t => t.CreatedUserId);

    }