code: public Object getOneRequired(Object locator) throws ReferenceException {
  		List<Object> components = find(Object.class, locator, true);
  		return components.size() > 0 ? components.get(0) : null;
  	}
docs: Gets a required component reference that matches specified locator.
  
  @param locator the locator to find a reference by.
  @return a matching component reference.
  @throws ReferenceException when no references found.