code: protected Map<String, String> attributesByBeanRef(String beanRef) {
        Map<String, String> result = null;
        for (Entry<String, String> e : map.entrySet()) {
           final String k = e.getKey();
           if (k.startsWith(beanRef) && k.startsWith(DOT, beanRef.length())) {
              if (result == null) {
                 result = new HashMap<String,String>();
              }
              result.put(k.substring(beanRef.length() + DOT.length()), e.getValue());
           }
        }
        if (result == null) {
           return Collections.emptyMap();
        } else {
           return result;
        }
     }
docs: Return an attribute name to attribute value map
  
  @param beanRef
  @return