code: public static Set<String> references(final String value) {
  
          final HashSet<String> names = new HashSet<String>();
          if ((value == null) || (value.length() == 0)) {
              return names;
          }
  
          int end = -1;
          int from = 0;
          int start = -1;
          while ((start = value.indexOf("${", from)) > -1) {
              end = value.indexOf('}', start + 1);
              if (end == -1) {
                  // No closing bracket found...
                  from = value.length();
              } else {
                  names.add(value.substring(start + 2, end));
                  from = end + 1;
              }
          }
  
          return names;
  
      }
docs: Returns a set of references variables.
  
  @param value
  Value to parse - May be <code>null</code>.
  
  @return Referenced variable names - Never <code>null</code>, but may be empty.