code: public NlsFormatterPlugin<?> getFormatter(String formatType, String formatStyle) {
  
      NlsFormatterPlugin<?> result = null;
      Map<String, NlsFormatterPlugin<?>> style2builderMap = this.builders.get(formatType);
      if (style2builderMap != null) {
        result = style2builderMap.get(formatStyle);
        if ((result == null) && (formatStyle == null)) {
          result = style2builderMap.get(NlsFormatterManager.STYLE_MEDIUM);
        }
      }
      return result;
    }
docs: @see net.sf.mmm.util.nls.api.NlsFormatterManager#getFormatter(String, String)
  
  @param formatType is the type to be formatted.
  @param formatStyle is the style defining details of formatting. May be {@code null} for default formatter
  of the given {@code formatType}.
  @return the according {@link NlsFormatter} instance or {@code null} if NO such {@link NlsFormatter} is
  {@link #registerFormatter(NlsFormatterPlugin, String, String) registered} .