Update sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/batching/FlowControllerTest.java

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: NiranjanKumar001

sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/batching/FlowControllerTest.java

@@ -780,7 +780,7 @@ void testExceptionGetMessage() {
     FlowController.MaxOutstandingElementCountReachedException elementException =
         new FlowController.MaxOutstandingElementCountReachedException(100);
     assertThat(elementException.getMessage())
-        .isEqualTo("The maximum number of batch elements: 100 have been reached.");
+        .isEqualTo("The maximum number of batch elements: 100 has been reached.");
 
     FlowController.MaxOutstandingRequestBytesReachedException bytesException =
         new FlowController.MaxOutstandingRequestBytesReachedException(500);