@Override
  public Optional<File> getFromEnvironment(
      final Map<String, String> environment, final CommandLine commandLine) {
    final File toml = new File(environment.get(CONFIG_FILE_ENV_NAME));
    if (!toml.exists()) {
      throw new CommandLine.ParameterException(
          commandLine,
          String.format(
              "TOML file %s specified in environment variable %s not found",
              CONFIG_FILE_ENV_NAME, environment.get(CONFIG_FILE_ENV_NAME)));
    }
    return Optional.of(toml);
  }
Gets the configuration file from the environment variable.

@param environment the environment variables
@param commandLine the command line
@return an Optional containing the configuration file, or an empty Optional if the
    configuration file was not specified in the environment variable
app/src/main/java/org/hyperledger/besu/cli/util/ConfigFileFinder.java