code: public static Map<Property, Object> loadProperties(final String filename, final boolean addProperties) {
  		final InputStream input = ConfigLoader.class.getClassLoader().getResourceAsStream(filename);
  		if (input != null) {
  			return loadProperties(input, addProperties);
  		}
  		LOGGER.debug("Property file not found on classpath, skipping config file");
  		return new HashMap<>();
  	}
docs: Loads properties from property file on the classpath, if provided. Calling this method only has effect on new Email and Mailer instances after
  this.
  
  @param filename      Any file that is on the classpath that holds a list of key=value pairs.
  @param addProperties Flag to indicate if the new properties should be added or replacing the old properties.
  @return The updated properties map that is used internally.