JWTUtils

public JWTUtils(String issuer, String key, String secret) {
    this.ISSUER = issuer;
    this.CONSUMER_KEY = key;
    this.CONSUMER_SECRET = secret;
}

public JsonToken createToken(HashMap<String, String> keyValues) throws InvalidKeyException, SignatureException {
    JsonToken token;

    //Current time and signing algorithm
    Calendar cal = Calendar.getInstance();
    HmacSHA256Signer signer = new HmacSHA256Signer(ISSUER, CONSUMER_KEY, CONSUMER_SECRET.getBytes());

    //Configure JSON token
    token = new JsonToken(signer);
    token.setIssuedAt(new Instant(cal.getTimeInMillis()));
    token.setExpiration(new Instant(cal.getTimeInMillis() + 86400L)); // one day

    //Configure request object, which provides information of the item
    JsonObject payload = token.getPayloadAsJsonObject();
    for (String key : keyValues.keySet()) {
        payload.addProperty(key, keyValues.get(key));
    }

    return token;
}