style: formatting fix in MultiGroupTest.java

Author: jponge

implementation/src/test/java/io/smallrye/mutiny/operators/MultiGroupTest.java

@@ -1049,7 +1049,7 @@ void testUpstreamRequestsNotBlownOutOfProportion() {
             AtomicLong itemCounter = new AtomicLong(0);
             AtomicReference<MultiEmitter<? super Integer>> e = new AtomicReference<>();
 
-            Multi.createFrom().<Integer>emitter(e::set)
+            Multi.createFrom().<Integer> emitter(e::set)
                     .onRequest().invoke(requestCounter::addAndGet)
                     .group().by(i -> i / 10)
                     .onItem().transformToMulti(g -> g.map(i -> g.key() + " : " + i)