docs: private Object getFormatter() {
          Object f = iFormatter;
  
          if (f == null) {
              if (iElementPairs.size() == 2) {
                  Object printer = iElementPairs.get(0);
                  Object parser = iElementPairs.get(1);
  
                  if (printer != null) {
                      if (printer == parser || parser == null) {
                          f = printer;
                      }
                  } else {
                      f = parser;
                  }
              }
  
              if (f == null) {
                  f = new Composite(iElementPairs);
              }
  
              iFormatter = f;
          }
  
          return f;
      }