unable to handle pinniped-provided mTLS credentials

[pktxu]

Describe the bug

Trying to auth against a pinniped-enabled cluster with 6.10-SNAPSHOT results (after building with bouncycastle to use EC keys) in:

Caused by: java.lang.ClassCastException: class org.bouncycastle.asn1.pkcs.PrivateKeyInfo cannot be cast to class org.bouncycastle.openssl.PEMKeyPair (org.bouncycastle.asn1.pkcs.PrivateKeyInfo and org.bouncycastle.openssl.PEMKeyPair are in unnamed module of loader 'app')
	at io.fabric8.kubernetes.client.internal.CertUtils$1.call(CertUtils.java:188)
	at io.fabric8.kubernetes.client.internal.CertUtils.handleECKey(CertUtils.java:195)
	at io.fabric8.kubernetes.client.internal.CertUtils.loadKey(CertUtils.java:170)
	at io.fabric8.kubernetes.client.internal.CertUtils.createKeyStore(CertUtils.java:146)
	at io.fabric8.kubernetes.client.internal.CertUtils.createKeyStore(CertUtils.java:288)
	at io.fabric8.kubernetes.client.internal.SSLUtils.keyManagers(SSLUtils.java:188)
	at io.fabric8.kubernetes.client.internal.SSLUtils.keyManagers(SSLUtils.java:177)
	at io.fabric8.kubernetes.client.utils.HttpClientUtils.applyCommonConfiguration(HttpClientUtils.java:188)
	at io.fabric8.kubernetes.client.okhttp.OkHttpClientFactory.newBuilder(OkHttpClientFactory.java:82)
	at io.fabric8.kubernetes.client.okhttp.OkHttpClientFactory.newBuilder(OkHttpClientFactory.java:29)
	at io.fabric8.kubernetes.client.KubernetesClientBuilder.getHttpClient(KubernetesClientBuilder.java:90)
	at io.fabric8.kubernetes.client.KubernetesClientBuilder.build(KubernetesClientBuilder.java:79)

Fabric8 Kubernetes Client version

SNAPSHOT

Steps to reproduce

1. Get a kubeconfig through pinniped
2. examine the credentials through yq '.credentials[0].credential.clientKeyData' ~/.config/pinniped/credentials.yaml | openssl ec -text -noout
3. Try to use a client built using pinniped's kubeconfig
4. see it fail with the above stacktrace

Expected behavior

Client building to succeed

Runtime

other (please specify in additional context)

Kubernetes API Server version

1.25.3@latest

Environment

Amazon

Fabric8 Kubernetes Client Logs

No response

Additional context

No response