code: public Object printHelpMessage(CommandLine commandLine, PrintStream stream) {
          commandLine.usage(stream);
          return null;
      }
docs: If an &#064;Option whose {@code usageHelp} attribute is annotated as true appears in the arguments.
  then the script body is not run and this {@code printHelpMessage} method is called instead.
  The default behavior is to print the {@link CommandLine#usage(PrintStream)} to the specified stream.
  The return value becomes the return value for the Script.run which will be the exit code
  if we've been called from the command line.
  
  @param commandLine The CommandLine instance
  @param stream the stream to print the usage help message to
  @return The value that Script.run should return ({@code null} by default).
  @since 3.0