public TlsKeyPair tlsKeyPair() {
        if (tlsKeyPair == null) {
            tlsKeyPair = TlsKeyPair.of(privateKey(), certificate());
        }
        return tlsKeyPair;
    }
Returns the {@link TlsKeyPair} of the self-signed certificate.
junit5/src/main/java/com/linecorp/armeria/internal/testing/SelfSignedCertificateRuleDelegate.java