code: public static Collection<String> getPropertyValue(Properties properties, String propertyName,
              Collection<String> defaultValue) {
          Collection<String> result = defaultValue;
          String propertyValue = properties.getProperty(propertyName);
          if (propertyValue != null) {
              result = toCollection(propertyValue);
              if (result.contains("*") && result.size() > 1) {
                  throw new ConfigurationException(propertyName + " must be a comma-separated list or *");
              }
          }
          return result;
      }
docs: Retrieves a property containing a comma separated list of values, trim them and return them as a Collection of
  String.
  
  @param properties
  @param propertyName
  @param defaultValue
  @return the values