"No key data found" when using pgpainless to import key

I'm on Mac and I've created and exported a key:

% gpg --generate-key
% gpg --export --armor --output new.pub B42B1AF5 

the contents of which you can see here:

-----BEGIN PGP PUBLIC KEY BLOCK-----
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=sKDL
-----END PGP PUBLIC KEY BLOCK-----

My code, using the PGPainless-SOP library:

import sop.SOP;

SOP sop = new SOPImpl();
byte[] cert = sop.extractCert()
        .key(new FileInputStream(encryptionKeyPath))
        .getBytes();

The dependency:

<dependency>
    <groupId>org.pgpainless</groupId>
    <artifactId>pgpainless-sop</artifactId>
    <version>1.7.2</version>
</dependency>

The exception:

sop.exception.SOPGPException$BadData: org.bouncycastle.openpgp.PGPException: No key data found.

    at org.pgpainless.sop.KeyReader$Companion.readSecretKeys(KeyReader.kt:39)
    at org.pgpainless.sop.ExtractCertImpl.key(ExtractCertImpl.kt:22)
    at con.com.pkg.uploader.utils.app.encryptInputStream(Utils.java:94)
    at con.com.pkg.uploader.utils.app.encryptInputStreamTest(UtilsTest.java:22)
Caused by: org.bouncycastle.openpgp.PGPException: No key data found.
    ... 45 more

Why is no key data found? I've tried with another key too, same result.

Looking at the documentation reveals the mistake. Using the terminology of OpenPGP and the package authors, the extractCert() method gets a public key (certificate) from a secret key, but you don't have that. Instead, you have an armored public key.

To get a certificate from the armored public key, use PGPainless.readKeyRing().publicKeyRing():

PGPPublicKeyRing cert = PGPainless.readKeyRing().publicKeyRing(PGP_PUBKEY);