anchor.diff:  
   The `headerHeading` and `footerHeading` may contain format specifiers. See <<Section Headings>>.
   
  -=== Section Headings
  +==== Section Headings
   Section headers can be used to make usage message layout appear more spacious. Section headings may contain embedded line separator (`%n`) format specifiers:
   [source,java]
   ----
  
positive.code: class Ln { ... }
  ----
  
  === Header and Footer
  The `header` will be shown at the top of the usage help message (before the synopsis). The first header line is also the line shown in the subcommand list if your command has subcommands (see <<Usage Help for Subcommands>>).
  
  Use the `footer` attribute to specify one or more lines to show below the generated usage help message.
  
negative.code:       files   files to transfer
  ----
  
  ==== Show Default Values
  ===== `${DEFAULT-VALUE}` Variable
  The link:http://picocli.info/#_default_values[default value] for an option or positional parameter
  can be embedded in the description by specifying the variable `${DEFAULT-VALUE}` in the description text.
  
  