How to create a PKCS7/CMS signature using BouncyCastle

PKCS7.java

package scratch;

import java.io.FileInputStream;
import java.io.IOException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.Provider;
import java.security.Security;
import java.security.UnrecoverableKeyException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

import org.bouncycastle.cert.X509CertificateHolder;
import org.bouncycastle.cms.CMSException;
import org.bouncycastle.cms.CMSProcessableByteArray;
import org.bouncycastle.cms.CMSSignedData;
import org.bouncycastle.cms.CMSSignedDataGenerator;
import org.bouncycastle.cms.CMSTypedData;
import org.bouncycastle.cms.jcajce.JcaSignerInfoGeneratorBuilder;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.operator.ContentSigner;
import org.bouncycastle.operator.OperatorCreationException;
import org.bouncycastle.operator.jcajce.JcaContentSignerBuilder;
import org.bouncycastle.operator.jcajce.JcaDigestCalculatorProviderBuilder;

public class Pkcs7 {
    private static final String KEYSTORE_FILENAME = "...";
    private static final String KEYSTORE_PASSWORD = "...";
    private static final String KEY_ALIAS = "...";
    private static final String KEY_PASSWORD = "...";

    public static void main(String[] args) throws OperatorCreationException,
            IOException,
            CMSException,
            KeyStoreException,
            NoSuchAlgorithmException,
            CertificateException,
            UnrecoverableKeyException {
        String data = "Hello";

        // Get keys and provider. If using a token or something, this would be
        // different.
        Security.addProvider(new BouncyCastleProvider());
        KeyStore keystore = KeyStore.getInstance("PKCS12");
        try (var keystoreContents = new FileInputStream(KEYSTORE_FILENAME)) {
            keystore.load(keystoreContents, KEYSTORE_PASSWORD.toCharArray());
        }
        Provider provider = Security.getProvider("BC");
        PrivateKey key = (PrivateKey) keystore.getKey(KEY_ALIAS,
                KEY_PASSWORD.toCharArray());
        X509Certificate cert = (X509Certificate) keystore
                .getCertificate(KEY_ALIAS);

        // Create the signature
        CMSTypedData msg = new CMSProcessableByteArray(data.getBytes());
        CMSSignedDataGenerator signedDataGen = new CMSSignedDataGenerator();
        X509CertificateHolder signCert = new X509CertificateHolder(
                cert.getEncoded());
        ContentSigner signer = new JcaContentSignerBuilder("SHA1withRSA")
                .setProvider(provider).build(key);
        signedDataGen.addSignerInfoGenerator(new JcaSignerInfoGeneratorBuilder(
                new JcaDigestCalculatorProviderBuilder().setProvider(provider)
                        .build()).build(signer, signCert));
                
        // add the signing cert to the signature
        Store<X509Certificate> certs = new JcaCertStore(Arrays.asList(cert)); 
        signedDataGen.addCertificates(certs);

        // false = create detached signature
        CMSSignedData signedData = signedDataGen.generate(msg, false);
        byte[] signatureBytes = signedData.getEncoded();

        org.apache.commons.io.HexDump.dump(signatureBytes, 0, System.out, 0);
    }
}

68: Store<X509Certificate> certs = new JcaCertStore(Arrays.asList(cert));

Imports seem to be missing for the classes used here. Is it org.bouncycastle.cert.jcajce.JcaCertStore and org.bouncycastle.util.Store?