Cannot look up attributes in a Point type object

class Point {
    has int $.x;
    has int $.y;

    method new( int $x, int $y ) {
    return self.bless( :$x, :$y );
    }

    method is-close( Point $other, Numeric $close = 5 ) returns Bool {
    return ($.x - $other.x)**2 + ($.y - $other.y)**2 < $close;
    }
}

class Line {
    has Point $.p1;
    has Point $.p2;
    has Bool $.is-short;

    method new( Point $p1, Point $p2 ) {
    return self.bless( :$p1, :$p2 );
    }

    submethod BUILD() {
    $!is-short = $!p1.is-close( $!p2 );
    }
}

my $p1 = Point.new(1,2);
my $p2 = Point.new(2,3);
say $p1.is-close($p2);

my $line = Line.new( $p1, $p2 );
say $line.is-short;