@Override
    public String execute(CommandContext commandContext, String[] args) {
        if (ArrayUtils.isNotEmpty(args)) {
            return processedTable.computeIfAbsent(args[0], this::commandHelp);
        } else {
            return processedTable.computeIfAbsent(MAIN_HELP, commandName -> mainHelp());
        }
    }
@Test
    void testGreeting() {
        Help help = new Help(FrameworkModel.defaultModel());
        String output = help.execute(Mockito.mock(CommandContext.class), new String[] {"greeting"});
        assertThat(output, containsString("COMMAND NAME"));
        assertThat(output, containsString("greeting"));
        assertThat(output, containsString("EXAMPLE"));
        assertThat(output, containsString("greeting dubbo"));
    }