Container's one method is returning a single Object object instead of an array reference with a single Object object inside.

The fix is quite simple:

sub one {
  my $self = shift;
  my $filter = shift;
  return [ grep { $_->{'value'} == $filter } @{$self->{'objects'}} ];
}
[download]

Output:

container=Container=HASH(0x1cc2e10)
all:

Object=HASH(0x1cdf6b0) name is foo

Object=HASH(0x1cdf788) name is bar

one:

Object=HASH(0x1cdf6b0) name is foo