Fallback to BKS when JKS is not available

This is the case on e.g. Android. BKS is BouncyCastles JKS-compatible implementation of a KeyStore

util/src/main/java/io/kubernetes/client/util/SSLUtils.java

@@ -179,7 +179,17 @@ public static KeyStore createKeyStore(
 
     PrivateKey privateKey = loadKey(keyInputStream, clientKeyAlgo);
 
-    KeyStore keyStore = KeyStore.getInstance("JKS");
+    KeyStore keyStore;
+    try {
+        keyStore = KeyStore.getInstance("JKS");
+    }
+    catch(KeyStoreException e) {
+        // Not having an instance of JKS happens on Android, for example.
+        // Since we rely on BouncyCastle anyway, let's try BKS instead
+        // (which is BouncyCastle's JKS compatible provider).
+        keyStore = KeyStore.getInstance("BKS");
+    }
+
     if (keyStoreFile != null && keyStoreFile.length() > 0) {
       keyStore.load(new FileInputStream(keyStoreFile), keyStorePassphrase);
     } else {