Generics without parameterless constructors

Can someone explain why in the code below, class1List does not require class1 to have a parameterless constructor, but class2list does require class 2 to have a parameterless constructor.

unit Unit11;

interface

uses
  System.Generics.Collections;

type
  class1 = class
  public
    constructor Create( const i : integer ); virtual;
  end;

  class1List<T : class1 > = class( TObjectList< T > )
  public
    function AddChild( const i : integer ) : T;
  end;

  class2 = class
  public
    constructor Create( const i : integer );
  end;

  class2List<T : class2 > = class( TObjectList< T > )
  public
    function AddChild( const i : integer ) : T;
  end;


implementation

{ class1List<T> }

function class1List<T>.AddChild(const i: integer): T;
begin
  Result := T.Create( i );
  inherited Add( Result );
end;

{ class2List<T> }

function class2List<T>.AddChild(const i: integer): T;
begin
  Result := T.Create( i );
  inherited Add( Result );
end;

{ class1 }

constructor class1.Create(const i: integer);
begin

end;

{ class2 }

constructor class2.Create(const i: integer);
begin

end;

end.