fix: return type of max commit delay option. (#2953)

* Use `TransactionOption` as return type instead of `TransactionOption`

Author: arpan14

google-cloud-spanner/clirr-ignored-differences.xml

@@ -605,6 +605,14 @@
     <method>com.google.cloud.spanner.admin.instance.v1.stub.InstanceAdminStubSettings getInstanceAdminStubSettings()</method>
   </difference>
 
+  <!-- (Modify return type of maxCommitDelay. Feature not announced) -->
+  <difference>
+    <differenceType>7006</differenceType>
+    <className>com/google/cloud/spanner/Options</className>
+    <method>com.google.cloud.spanner.Options$ReadQueryUpdateTransactionOption maxCommitDelay(java.time.Duration)</method>
+    <to>com.google.cloud.spanner.Options$TransactionOption</to>
+  </difference>
+
   <difference>
     <differenceType>7005</differenceType>
     <className>com/google/cloud/spanner/PartitionedDmlTransaction</className>

google-cloud-spanner/src/main/java/com/google/cloud/spanner/Options.java

@@ -141,7 +141,7 @@ public static ReadQueryUpdateTransactionOption priority(RpcPriority priority) {
     return new PriorityOption(priority);
   }
 
-  public static ReadQueryUpdateTransactionOption maxCommitDelay(Duration maxCommitDelay) {
+  public static TransactionOption maxCommitDelay(Duration maxCommitDelay) {
     Preconditions.checkArgument(!maxCommitDelay.isNegative(), "maxCommitDelay should be positive");
     return new MaxCommitDelayOption(maxCommitDelay);
   }
@@ -258,8 +258,7 @@ void appendToOptions(Options options) {
   static final CommitStatsOption COMMIT_STATS_OPTION = new CommitStatsOption();
 
   /** Option to request {@link MaxCommitDelayOption} for read/write transactions. */
-  static final class MaxCommitDelayOption extends InternalOption
-      implements ReadQueryUpdateTransactionOption {
+  static final class MaxCommitDelayOption extends InternalOption implements TransactionOption {
     final Duration maxCommitDelay;
 
     MaxCommitDelayOption(Duration maxCommitDelay) {