docs: public String getConfig(String key) throws MojoExecutionException {
  		ResourceBundle resource = null;
  		try {
  			resource = ResourceBundle.getBundle(
  					"io/sarl/maven/compiler/config", //$NON-NLS-1$
  					java.util.Locale.getDefault(),
  					MavenHelper.class.getClassLoader());
  		} catch (MissingResourceException e) {
  			throw new MojoExecutionException(e.getLocalizedMessage(), e);
  		}
  		String value = resource.getString(key);
  		if (value == null || value.isEmpty()) {
  			value = Strings.nullToEmpty(value);
  			this.log.warn(MessageFormat.format(Messages.MavenHelper_1, key));
  		}
  		return value;
  	}