Classes/Console/Mvc/Controller/CommandController.php
protected function callCommandMethod()
    {
        $preparedArguments = [];
        foreach ($this->arguments as $argument) {
            $preparedArguments[] = $argument->getValue();
        }
        $commandResult = $this->{$this->commandMethodName}(...$preparedArguments);
        if ($commandResult !== null) {
            $this->outputLine((string)$commandResult);
            $this->output->getSymfonyConsoleOutput()->getErrorOutput()->writeln('<warning>Returning a string from a command method is deprecated.</warning>');
            $this->output->getSymfonyConsoleOutput()->getErrorOutput()->writeln('<warning>Please use $this->outputLine() instead.</warning>');
        }
    }
protected function callCommandMethod()
    {
        $preparedArguments = [];
        foreach ($this->arguments as $argument) {
            $preparedArguments[] = $argument->getValue();
        }
        $commandResult = $this->{$this->commandMethodName}(...$preparedArguments);
        if ($commandResult !== null) {
            $this->outputLine((string)$commandResult);
            $this->output->getSymfonyConsoleOutput()->getErrorOutput()->writeln('<warning>Returning a string from a command method is deprecated.</warning>');
            $this->output->getSymfonyConsoleOutput()->getErrorOutput()->writeln('<warning>Please use $this->outputLine() instead.</warning>');
        }
    }
Calls the specified command method and passes the arguments.

If the command returns a string, it is appended to the content in the
response object. If the command doesn't return anything and a valid
view exists, the view is rendered automatically.