code: @Nullable
    public IMimeType getPrimaryMimeTypeForFilename (@Nonnull @Nonempty final String sFilename)
    {
      ValueEnforcer.notEmpty (sFilename, "Filename");
  
      final String sExtension = FilenameHelper.getExtension (sFilename);
      return getPrimaryMimeTypeForExtension (sExtension);
    }
docs: Get the primary (=first) mime type associated with the specified filename.
  
  @param sFilename
  The filename to retrieve the primary mime type from. May neither be
  <code>null</code> nor empty.
  @return <code>null</code> if no mime type is associated with the extension
  of the passed filename