src/ConfigProvider.php
public function setCustomConfigurationOptions(array $customConfigurationOptions): void
    {
        if ($this->config !== null) {
            throw new \RuntimeException(
                'Custom configuration options can be set only before initialization of configuration'
            );
        }

        $this->customConfigurationOptions = $customConfigurationOptions;
    }
public function setCustomConfigurationOptions(array $customConfigurationOptions): void
    {
        if ($this->config !== null) {
            throw new \RuntimeException(
                'Custom configuration options can be set only before initialization of configuration'
            );
        }

        $this->customConfigurationOptions = $customConfigurationOptions;
    }
Add custom configuration options that should be added to the default ones.
Can be set only before initialization, because the configuration is then immutable.

Note you cannot override the default configuration options.

@param array $customConfigurationOptions Array with values = configuration options (environment variables)