Validation failed for Maybe[ArrayRef[Planet::Earth::Country]] with value [ "Brazil", "Paraguay", "Uruguay" ]

Attribute (countries) does not pass the type constraint because: Validation failed for 'Maybe[ArrayRef[Planet::Earth::Country]]' with value [ "Brazil", "Paraguay", "Uruguay" ] at /usr/lib/x86_64-linux-gnu/perl5/5.20/Moose/Exception.pm line 37
	Moose::Exception::_build_trace('Moose::Exception::ValidationFailedForInlineTypeConstraint=HASH(0x4742fa8)') called at reader Moose::Exception::trace (defined at /usr/lib/x86_64-linux-gnu/perl5/5.20/Moose/Exception.pm line 9) line 8
	Moose::Exception::trace('Moose::Exception::ValidationFailedForInlineTypeConstraint=HASH(0x4742fa8)') called at /usr/lib/x86_64-linux-gnu/perl5/5.20/Moose/Exception.pm line 49
	Moose::Exception::BUILD('Moose::Exception::ValidationFailedForInlineTypeConstraint=HASH(0x4742fa8)', 'HASH(0x4725478)') called at /usr/lib/x86_64-linux-gnu/perl5/5.20/Class/MOP/Method.pm line 126
	Class::MOP::Method::execute('Moose::Meta::Method=HASH(0x41c17f8)', 'Moose::Exception::ValidationFailedForInlineTypeConstraint=HASH(0x4742fa8)', 'HASH(0x4725478)') called at /usr/lib/x86_64-linux-gnu/perl5/5.20/Moose/Object.pm line 55
	Moose::Object::BUILDALL('Moose::Exception::ValidationFailedForInlineTypeConstraint=HASH(0x4742fa8)', 'HASH(0x4725478)') called at /usr/lib/x86_64-linux-gnu/perl5/5.20/Moose/Meta/Class.pm line 281
	Moose::Meta::Class::new_object('Moose::Meta::Class=HASH(0x4742fc0)', 'HASH(0x4725478)') called at /usr/lib/x86_64-linux-gnu/perl5/5.20/Moose/Object.pm line 26
	Moose::Object::new('Moose::Exception::ValidationFailedForInlineTypeConstraint', 'type_constraint_message', 'Validation failed for \'Maybe[ArrayRef[Planet::Earth::Country]]\' with value [ "Brazil", "Paraguay", "Uruguay" ]', 'class_name', 'Planet::Earth::Continent', 'attribute_name', 'countries', 'value', 'ARRAY(0x2612ec8)') called at reader Planet::Earth::Continent::countries (defined at Planet/Earth/Continent.pm line 6) line 15
	Planet::Earth::Continent::countries('Planet::Earth::Continent=HASH(0x4724cb0)') called at test.pl line 15