private function formatPropertyMappings(iterable $propertyMappings)
    {
        $output = [];

        foreach ($propertyMappings as $propertyName => $property) {
            $output[] = $this->formatField(sprintf('  %s', $propertyName), '');

            if ($property instanceof FieldMetadata) {
                $output = array_merge($output, $this->formatColumn($property));
            } elseif ($property instanceof AssociationMetadata) {
                // @todo guilhermeblanco Fix me! We are trying to iterate through an AssociationMetadata instance
                foreach ($property as $field => $value) {
                    $output[] = $this->formatField(sprintf('    %s', $field), $this->formatValue($value));
                }
            }
        }

        return $output;
    }