code: public StringBuffer format(Object obj, StringBuffer toAppendTo, FieldPosition pos)
      {
  
          if (obj == null)
              return null;
  
          return toAppendTo.append(this.format(obj.toString()));
  
      }
docs: /*
  (non-Javadoc)
  
  @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer,
  java.text.FieldPosition)