Signature OAuth 1.0 invalid caracter

Question

I am using the implementation example for two-legged authentication. Based on the Absolute minimum code to get a valid oauth_signature populated in Java or Groovy? implementation. However, I have a problem when the secret key has the character "#", I will exemplify.

For this test data, it works perfectly ..

nonce = 54408462
timestamp = 1589925486
url https://test.com/test
secretKey: Test123
key: test
generated signature: 19Cuj9dwWFmROc3Snxg5awltK10=

However when it has a character "#"...

nonce = 92475502
timestamp = 1589925554
url https://test.com/test
secretKey: Test#123
key: test
generated signature: 87QlLaFOZRsMMkJq3FGozFRNdJ0=

signature that should have been generated: OUl0yBF5sBv3/0uB0YIoTRPnrCM=

seems to me to be something of encoding, but I can't get it right

public String buildAuthorization(String url) {

    String oauth_nonce = "" + (int) (Math.random() * 100000000);
    String oauth_timestamp = "" + (System.currentTimeMillis() / 1000);
    List<BasicNameValuePair> qparams = new ArrayList<>();
    qparams.add(new BasicNameValuePair(OAUTH_CONSUMER_KEY, key));
    qparams.add(new BasicNameValuePair(OAUTH_NONCE, oauth_nonce));
    qparams.add(new BasicNameValuePair(OAUTH_SIGNATURE_METHOD, HMAC_SHA_1));
    qparams.add(new BasicNameValuePair(OAUTH_TIMESTAMP, oauth_timestamp));
    qparams.add(new BasicNameValuePair(OAUTH_VERSION, "1.0"));
    String signature = "";
    try {
        signature = getSignature(URLEncoder.encode(url, "UTF-8"), secret,
                URLEncoder.encode(URLEncodedUtils.format(qparams, "UTF-8"), "UTF-8"));
    } catch (IOException | NoSuchAlgorithmException | InvalidKeyException io) {
        throw new RuntimeException("Error");
    }

    return "OAuth "+OAUTH_CONSUMER_KEY+"=\"" + key + "\"," +
            OAUTH_SIGNATURE_METHOD+"=\"HMAC-SHA1\"," +
            OAUTH_TIMESTAMP+"=\"" + oauth_timestamp + "\"," +
            OAUTH_NONCE+"=\"" + oauth_nonce + "\"," +
            OAUTH_VERSION+"=\"1.0\"," +
            OAUTH_SIGNATURE + "=\"" + signature + "\"";

}

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;

public class OAuthPassword {

private static final String HMAC_SHA1 = "HmacSHA1";
private static final String ENC = "UTF-8";
private static Base64 base64 = new Base64();

public static String getSignature(String url, String secret, String params)
        throws UnsupportedEncodingException, NoSuchAlgorithmException,
        InvalidKeyException {

    StringBuilder base = new StringBuilder();
    base.append("POST&");
    base.append(url);
    base.append("&");
    base.append(params);
    byte[] keyBytes = (secret + "&").getBytes(ENC);
    SecretKey key = new SecretKeySpec(keyBytes, HMAC_SHA1);
    Mac mac = Mac.getInstance(HMAC_SHA1);
    mac.init(key);

    return new String(base64.encode(mac.doFinal(base.toString().getBytes(
            ENC))), ENC).trim();
}
}