code: public void execute() {
          try {
              if (downloadCommandOptions.species != null && !downloadCommandOptions.species.isEmpty()) {
                  // We need to get the Species object from the CLI name
                  // This can be the scientific or common name, or the ID
                  //            Species speciesToDownload = null;
                  for (Species sp : configuration.getAllSpecies()) {
                      if (downloadCommandOptions.species.equalsIgnoreCase(sp.getScientificName())
                              || downloadCommandOptions.species.equalsIgnoreCase(sp.getCommonName())
                              || downloadCommandOptions.species.equalsIgnoreCase(sp.getId())) {
                          species = sp;
                          break;
                      }
                  }
  
                  // If everything is right we launch the download
                  if (species != null) {
                      processSpecies(species);
                  } else {
                      logger.error("Species '{}' not valid", downloadCommandOptions.species);
                  }
              } else {
                  logger.error("--species parameter '{}' not valid", downloadCommandOptions.species);
              }
          } catch (ParameterException e) {
              logger.error("Error in 'download' command line: " + e.getMessage());
          } catch (IOException | InterruptedException e) {
              logger.error("Error downloading '" + downloadCommandOptions.species + "' files: " + e.getMessage());
          }
  
      }
docs: Execute specific 'download' command options.