code: public List<Object> getRequired(Object locator) throws ReferenceException {
  		return find(Object.class, locator, true);
  	}
docs: Gets all component references that match specified locator. At least one
  component reference must be present. If it doesn't the method throws an
  error.
  
  @param locator the locator to find references by.
  @return a list with matching component references.
  
  @throws ReferenceException when no references found.