fix: use ThreadLocalRandom for backoff jitter, disable OkHttp retry, strengthen test assertions

Replace the shared static Random instance with ThreadLocalRandom.current()
at the backoff call site and for the fan-out name generator in
MinioAsyncClient — eliminating shared-state CAS contention under concurrent
retry load.

Disable OkHttp's retryOnConnectionFailure in doExecuteAsync so the SDK's
executeWithRetry is the sole retry policy; previously OkHttp could silently
add an extra attempt on stale-connection IOExceptions, causing more total
attempts than maxRetries.

Strengthen the two remaining assertNotNull catch blocks in RetryTest
(testMaxRetriesOneDisablesRetry, testSetMaxRetriesPostConstruction) to typed
InvalidResponseException catches with responseCode()==500 assertions,
matching the pattern applied to the other tests in the previous commit.

Author: allanrogerr

api/src/main/java/io/minio/BaseS3Client.java

@@ -51,17 +51,16 @@
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.nio.charset.StandardCharsets;
-import java.security.SecureRandom;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Locale;
 import java.util.Map;
-import java.util.Random;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionException;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
@@ -94,7 +93,6 @@ public abstract class BaseS3Client implements AutoCloseable {
       "ServerSideEncryptionConfigurationNotFoundError";
   // maximum allowed bucket policy size is 20KiB
   protected static final int MAX_BUCKET_POLICY_SIZE = 20 * 1024;
-  protected static final Random RANDOM = new Random(new SecureRandom().nextLong());
   protected static final ObjectMapper OBJECT_MAPPER =
       JsonMapper.builder()
           .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
@@ -318,7 +316,7 @@ private CompletableFuture<Response> executeWithRetry(
               if (attempt + 1 >= maxAttempts || !Retry.isRetryable(cause)) {
                 return Utils.<Response>failedFuture(cause);
               }
-              long delayMs = Retry.computeBackoffMs(attempt + 1, RANDOM);
+              long delayMs = Retry.computeBackoffMs(attempt + 1, ThreadLocalRandom.current());
               CompletableFuture<Response> retryFuture = new CompletableFuture<>();
               RETRY_SCHEDULER.schedule(
                   () ->
@@ -351,7 +349,8 @@ private CompletableFuture<Response> doExecuteAsync(Http.S3Request s3request, Str
     PrintWriter traceStream = this.traceStream;
     if (traceStream != null) traceStream.print(request.httpTraces());
 
-    OkHttpClient httpClient = this.httpClient;
+    OkHttpClient httpClient =
+        this.httpClient.newBuilder().retryOnConnectionFailure(false).build();
     okhttp3.Request httpRequest = request.httpRequest();
     CompletableFuture<Response> completableFuture = newCompleteableFuture();
     httpClient

api/src/main/java/io/minio/MinioAsyncClient.java

@@ -93,6 +93,7 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.atomic.AtomicBoolean;
 import okhttp3.HttpUrl;
 import okhttp3.MediaType;
@@ -3370,7 +3371,7 @@ public CompletableFuture<PutObjectFanOutResponse> putObjectFanOut(PutObjectFanOu
               // Build POST object data
               String objectName =
                   "fan-out-"
-                      + new BigInteger(32, RANDOM).toString(32)
+                      + new BigInteger(32, ThreadLocalRandom.current()).toString(32)
                       + "-"
                       + System.currentTimeMillis();
               PostPolicy policy =

api/src/test/java/io/minio/RetryTest.java

@@ -459,8 +459,8 @@ public void testMaxRetriesOneDisablesRetry() throws Exception {
       try {
         client.listBuckets();
         Assert.fail("expected exception");
-      } catch (Exception e) {
-        Assert.assertNotNull("expected non-null exception", e);
+      } catch (InvalidResponseException e) {
+        Assert.assertEquals(500, e.responseCode());
       }
       // maxRetries=1 means a single attempt; must not retry
       Assert.assertEquals(1, server.getRequestCount());
@@ -481,8 +481,8 @@ public void testSetMaxRetriesPostConstruction() throws Exception {
       try {
         client.listBuckets();
         Assert.fail("expected exception");
-      } catch (Exception e) {
-        Assert.assertNotNull("expected non-null exception", e);
+      } catch (InvalidResponseException e) {
+        Assert.assertEquals(500, e.responseCode());
       }
       Assert.assertEquals(1, server.getRequestCount());
     }