validateIniKey()
                
                validateIniKey(string  $key, string  $value = null) : array
                Parse configuration values.
                Set default value for key if given value is null.
                                    Parameters
                    
                                                    
                                | string | $key | Config. entry name. | 
                                                    
                                | string | $value | Value to validate.. | 
                                            
                
                
                                    Returns
                    array
                                            — Configuration errors.