Use Hamcrest assertions instead of JUnit in microprofile/reactive-streams - backport main (helidon-io#1749) (helidon-io#6018)

Author: Captain1653

microprofile/reactive-streams/pom.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-    Copyright (c) 2019, 2022 Oracle and/or its affiliates.
+    Copyright (c) 2019, 2023 Oracle and/or its affiliates.
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
@@ -68,6 +68,11 @@
             <artifactId>junit-jupiter-api</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-all</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

microprofile/reactive-streams/src/test/java/io/helidon/microprofile/reactive/HelidonReactiveStreamsEngineTckTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020 Oracle and/or its affiliates.
+ * Copyright (c) 2020, 2023 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,9 @@
 import org.testng.annotations.BeforeClass;
 import org.testng.annotations.Test;
 
+import static org.hamcrest.CoreMatchers.notNullValue;
+import static org.hamcrest.MatcherAssert.assertThat;
+
 @Test
 public class HelidonReactiveStreamsEngineTckTest extends ReactiveStreamsTck<HelidonReactiveStreamsEngine> {
 
@@ -64,6 +67,6 @@ public void after() {
 
     @Test
     public void hasExecutor() {
-        org.testng.Assert.assertNotNull(executor);
+        assertThat(executor, notNullValue());
     }
 }