Interpolation of an empty variable %{} or %{::} should yield an empty string

The Hiera data provider should behave the same way as Hiera 3.0 when interpolating an empty string or a string that contains an empty name separator '::'. The interpolated expression should ignore leading and trailing whitespace.

%{} => ''

%{  } => ''

%{::} => ''

%{ :: } => ''

Leading and trailing whitespace will always be ignored in the Hiera dataprovider. So:

%{ some key }

will be considered exactly the same as:

%{some key}

In case that someone really want a leading or tralining space in the key, they can use the syntax:

%{scope(' some key ')}