code: @Nonnegative
    public static int getOccurrenceCountIgnoreCase (@Nullable final String sText,
                                                    @Nullable final String sSearch,
                                                    @Nonnull final Locale aSortLocale)
    {
      return sText != null && sSearch != null ? getOccurrenceCount (sText.toLowerCase (aSortLocale),
                                                                    sSearch.toLowerCase (aSortLocale))
                                              : 0;
    }
docs: Count the number of occurrences of sSearch within sText ignoring case.
  
  @param sText
  The text to search in. May be <code>null</code>.
  @param sSearch
  The text to search for. May be <code>null</code>.
  @param aSortLocale
  The locale to be used for case unifying.
  @return A non-negative number of occurrences.