code: public CommandLine setSeparator(String separator) {
          getCommandSpec().parser().separator(Assert.notNull(separator, "separator"));
          for (CommandLine command : getCommandSpec().subcommands().values()) {
              command.setSeparator(separator);
          }
          return this;
      }
docs: Sets the String the parser uses to separate option names from option values to the specified value.
  The separator may also be set declaratively with the {@link CommandLine.Command#separator()} annotation attribute.
  <p>The specified setting will be registered with this {@code CommandLine} and the full hierarchy of its
  subcommands and nested sub-subcommands <em>at the moment this method is called</em>. Subcommands added
  later will have the default setting. To ensure a setting is applied to all
  subcommands, call the setter last, after adding subcommands.</p>
  @param separator the String that separates option names from option values
  @see ParserSpec#separator(String)
  @return this {@code CommandLine} object, to allow method chaining