Changes:

Formatting, fixed a test failure occurring with a newly added test that
was merged in (logic error in my existing code)

core/src/main/java/org/apache/accumulo/core/fate/FateStore.java

@@ -23,6 +23,7 @@
 import java.io.IOException;
 import java.io.Serializable;
 import java.io.UncheckedIOException;
+import java.time.Duration;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -31,7 +32,6 @@
 
 import org.apache.accumulo.core.fate.zookeeper.ZooUtil;
 import org.apache.hadoop.io.DataInputBuffer;
-import java.time.Duration;
 
 /**
  * Transaction Store: a place to save transactions

core/src/main/java/org/apache/accumulo/core/fate/MetaFateStore.java

@@ -121,10 +121,6 @@ protected void create(FateId fateId, FateKey key) {
 
   @Override
   public Optional<FateTxStore<T>> tryReserve(FateId fateId) {
-    // return an empty option if the FateId doesn't exist
-    if (_getStatus(fateId).equals(TStatus.UNKNOWN)) {
-      return Optional.empty();
-    }
     // uniquely identify this attempt to reserve the fate operation data
     FateReservation reservation = FateReservation.from(lockID, UUID.randomUUID());
 

test/src/main/java/org/apache/accumulo/test/fate/MultipleStoresIT.java

@@ -25,6 +25,7 @@
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.io.File;
+import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
@@ -162,7 +163,7 @@ private void testReserveUnreserve(FateInstanceType storeType) throws Exception {
       reservation.setStatus(ReadOnlyFateStore.TStatus.SUBMITTED);
       assertEquals(ReadOnlyFateStore.TStatus.SUBMITTED, reservation.getStatus());
       reservation.delete();
-      reservation.unreserve(0, TimeUnit.MILLISECONDS);
+      reservation.unreserve(Duration.ofMillis(0));
       // Attempt to set a status on a tx that has been unreserved (should throw exception)
       assertThrows(IllegalStateException.class,
           () -> reservation.setStatus(ReadOnlyFateStore.TStatus.NEW));
@@ -179,8 +180,7 @@ public void testReserveNonExistentTxn() throws Exception {
 
   private void testReserveNonExistentTxn(FateInstanceType storeType) throws Exception {
     // Tests that reserve() doesn't hang indefinitely and instead throws an error
-    // on reserve() a non-existent transaction. Tests that tryReserve() will return
-    // an empty optional on non-existent transaction.
+    // on reserve() a non-existent transaction.
     final FateStore<SleepingTestEnv> store;
     final boolean isUserStore = storeType.equals(FateInstanceType.USER);
     final String tableName = getUniqueNames(1)[0];
@@ -195,7 +195,6 @@ private void testReserveNonExistentTxn(FateInstanceType storeType) throws Except
     }
 
     assertThrows(IllegalStateException.class, () -> store.reserve(fakeFateId));
-    assertTrue(store.tryReserve(fakeFateId).isEmpty());
   }
 
   @Test
@@ -238,12 +237,11 @@ private void testReserveReservedAndUnreserveUnreserved(FateInstanceType storeTyp
 
     // Unreserve all the FateIds
     for (var reservation : reservations) {
-      reservation.unreserve(0, TimeUnit.MILLISECONDS);
+      reservation.unreserve(Duration.ofMillis(0));
     }
     // Try to unreserve again (should throw exception)
     for (var reservation : reservations) {
-      assertThrows(IllegalStateException.class,
-          () -> reservation.unreserve(0, TimeUnit.MILLISECONDS));
+      assertThrows(IllegalStateException.class, () -> reservation.unreserve(Duration.ofMillis(0)));
     }
   }
 
@@ -282,7 +280,7 @@ private void testReserveAfterUnreserveAndReserveAfterDeleted(FateInstanceType st
 
     // Unreserve all
     for (var reservation : reservations) {
-      reservation.unreserve(0, TimeUnit.MILLISECONDS);
+      reservation.unreserve(Duration.ofMillis(0));
     }
 
     // Ensure they can be reserved again, and delete and unreserve this time
@@ -292,7 +290,7 @@ private void testReserveAfterUnreserveAndReserveAfterDeleted(FateInstanceType st
       var reservation = store.tryReserve(fateId);
       assertFalse(reservation.isEmpty());
       reservation.orElseThrow().delete();
-      reservation.orElseThrow().unreserve(0, TimeUnit.MILLISECONDS);
+      reservation.orElseThrow().unreserve(Duration.ofMillis(0));
     }
 
     for (FateId fateId : allIds) {

test/src/main/java/org/apache/accumulo/test/fate/meta/MetaFateInterleavingIT.java

@@ -39,6 +39,8 @@ public void executeTest(FateTestExecutor<FilTestEnv> testMethod, int maxDeferred
     String path = ZK_ROOT + Constants.ZFATE;
     ZooReaderWriter zk = sctx.getZooReaderWriter();
     zk.mkdirs(ZK_ROOT);
-    testMethod.execute(new MetaFateStore<>(path, zk), sctx);
+    testMethod.execute(
+        new MetaFateStore<>(path, zk, sctx.getZooCache(), AbstractFateStore.createDummyLockID()),
+        sctx);
   }
 }

test/src/main/java/org/apache/accumulo/test/fate/user/UserFateInterleavingIT.java

@@ -34,8 +34,8 @@ public void executeTest(FateTestExecutor<FilTestEnv> testMethod, int maxDeferred
     try (ClientContext client =
         (ClientContext) Accumulo.newClient().from(getClientProps()).build()) {
       createFateTable(client, table);
-      testMethod.execute(new UserFateStore<>(client, table, maxDeferred, fateIdGenerator),
-          getCluster().getServerContext());
+      testMethod.execute(new UserFateStore<>(client, table, AbstractFateStore.createDummyLockID(),
+          maxDeferred, fateIdGenerator), getCluster().getServerContext());
       client.tableOperations().delete(table);
     }
   }