code: @Nonnull
    public IMimeType getMimeTypeFromString (@Nullable final String s, @Nonnull final Charset aCharset)
    {
      return getMimeTypeFromString (s, aCharset, DEFAULT_MIME_TYPE);
    }
docs: Try to find the MIME type that matches the passed content string.
  
  @param s
  The content string to check. May be <code>null</code>.
  @param aCharset
  The charset used to convert the string to a byte array. May not be
  <code>null</code>.
  @return {@link #DEFAULT_MIME_TYPE} if no matching MIME type was found.
  Never <code>null</code>.