Ability to create empty hierarchy (for global config)

[nmaludy]

Affected Puppet, Ruby, OS and module versions/distributions

• Puppet: 6.0.4
• Distribution: CentOS 7
• Module version: 3.3.4

How to reproduce (e.g Puppet code you use)

  class { '::hiera':
    hiera_version      => '5',
    hiera5_defaults    => {
      'datadir'   => 'data',
      'data_hash' => 'yaml_data',
    },
    hierarchy          => [],
    puppet_conf_manage => false,
    eyaml              => true,
  }

What are you seeing

$ cat /etc/puppetlabs/puppet/hiera.yaml
# hiera.yaml Managed by Puppet
version: 5
defaults:
  datadir: data
  data_hash: yaml_data
hierarchy:

What behaviour did you expect instead

$ cat /etc/puppetlabs/puppet/hiera.yaml
# hiera.yaml Managed by Puppet
version: 5
defaults:
  datadir: data
  data_hash: yaml_data
hierarchy: []

Any additional information you'd like to impart

It would be great if an empty hierarchy was created when an empty array was passed in.