public static String decompress(final String zippedBase64Str) {
        return Unchecked.supplier(() -> {
            val bytes = EncodingUtils.decodeBase64(zippedBase64Str);
            try (val zi = new GZIPInputStream(new ByteArrayInputStream(bytes))) {
                return IOUtils.toString(zi, Charset.defaultCharset());
            }
        }).get();
    }
First decode base64 String to byte array, then use ZipInputStream to revert the byte array to a
string.

@param zippedBase64Str the zipped base 64 str
@return the string, or null
core/cas-server-core-util-api/src/main/java/org/apereo/cas/util/CompressionUtils.java