Interface that tags a ConfigValue that is not mergeable until after substitutions are resolved. Basically these are special ConfigValue that never appear in a resolved tree, like {@link ConfigSubstitution} and {@link ConfigDelayedMerge}.
# File lib/hocon/impl/unmergeable.rb, line 13 def unmerged_values raise Hocon::ConfigError::ConfigBugOrBrokenError, "subclasses of `Unmergeable` must implement `unmerged_values` (#{self.class})" end