Fix map access in method ConversionActionBean#isMimeTypeExportableToPDF

        // Check if there is any saved ConverterCheckResult for the desired
        // MIME type.
        if (pdfConverterForTypes.containsKey(mimetype)) {
            return pdfConverterForTypes.get(mimetype).isAvailable();
        }

        // Check if there is any saved ConverterCheckResult for the desired
        // MIME type.
        if (pdfConverterForTypes.containsValue(mimetype)) {
            return pdfConverterForTypes.get(mimetype).isAvailable();
        }