GH-389: Fix MockReceiverTest#consumerMethods failure with reactor-cor…

…e 3.5

Fixes: #389

Due to the change between `3.4.x` and `3.5.x` of `reactor-core`, the test would fail. 
The reason is that since `3.5` the prefetching strategy is less eager and the consumption would be paused due to lack of downstream requests. 
The assertion was to strict as in such scenarios not only the intended partition is paused but all of them. 
This relaxation makes the test pass against future reactor-core versions.

src/test/java/reactor/kafka/receiver/internals/MockReceiverTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2023 VMware Inc. or its affiliates, All Rights Reserved.
+ * Copyright (c) 2016-2024 VMware Inc. or its affiliates, All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -70,6 +70,7 @@
 import java.util.function.Function;
 import java.util.regex.Pattern;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.awaitility.Awaitility.await;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -1188,7 +1189,8 @@ public void consumerMethods() throws Exception {
         testConsumerMethod(c -> {
             Collection<TopicPartition> partitions = Collections.singleton(new TopicPartition(topic, 1));
             c.pause(partitions);
-            assertEquals(partitions, c.paused());
+            // Due to backpressure other partitions can be paused at the same moment in time
+            assertThat(c.paused()).containsAll(partitions);
             c.resume(partitions);
         });
         testConsumerMethod(c -> {