code: public static StringBuffer appendOpeningTag(StringBuffer buffer, String tag)
  	{
  		return appendOpeningTag(buffer, tag, EMPTY_MAP);
  	}
docs: Add an opening tag to a StringBuffer.
  
  If the buffer is null, a new one is created.
  
  @param buffer
  StringBuffer to fill
  @param tag
  the tag to open
  @return the buffer