Remove redundant legacy Java workarounds (#1361)

Some classes use workarounds for issues present in older JDKs that
Hazelcast no longer supports, and can be removed.

Issues:
- [JDK bug](https://bugs.openjdk.java.net/browse/JDK-8156584), fixed in
9
   - `TestJavaKeyStoreSecureStoreUtils`
- [JDK bug](https://bugs.java.com/bugdatabase/view_bug?bug_id=8234729),
fixed in [15 (see blocking
issues)](https://bugs.openjdk.org/browse/JDK-8171335) + only skips on 15
& 16 (nothing else) anyway
   - `DebeziumCdcIntegrationTest.java`
   - `AbstractMySqlCdcIntegrationTest.java`
   - `MySqlCdcNetworkIntegrationTest.java`
- JDK8 compiler issue (unknown root cause) - compiles properly now
   - `GrAggBuilder`
   - `GeneralHashJoinBuilder`
GitOrigin-RevId: 75141818062b1e790a201a597c760f634e1d2d4b

extensions/cdc-debezium/src/test/java/com/hazelcast/jet/cdc/DebeziumCdcIntegrationTest.java

@@ -34,7 +34,6 @@
 import io.debezium.connector.mysql.MySqlConnector;
 import io.debezium.connector.postgresql.PostgresConnector;
 import org.bson.Document;
-import org.junit.Assume;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
 import org.junit.runner.RunWith;
@@ -73,10 +72,6 @@ public class DebeziumCdcIntegrationTest extends AbstractCdcIntegrationTest {
 
     @Test
     public void mysql() throws Exception {
-        Assume.assumeFalse("https://github.com/hazelcast/hazelcast-jet/issues/2623, " +
-                        "https://github.com/hazelcast/hazelcast/issues/18800",
-                System.getProperty("java.version").matches("^1[56].*"));
-
         try (MySQLContainer<?> container = mySqlContainer()) {
             container.start();
 
@@ -154,10 +149,6 @@ private StreamSource<ChangeRecord> mySqlSource(MySQLContainer<?> container) {
 
     @Test
     public void mysql_simpleJson() {
-        Assume.assumeFalse("https://github.com/hazelcast/hazelcast-jet/issues/2623, " +
-                        "https://github.com/hazelcast/hazelcast/issues/18800",
-                System.getProperty("java.version").matches("^1[56].*"));
-
         try (MySQLContainer<?> container = mySqlContainer()) {
             container.start();
 

extensions/cdc-mysql/src/test/java/com/hazelcast/jet/cdc/mysql/AbstractMySqlCdcIntegrationTest.java

@@ -21,8 +21,6 @@
 import com.hazelcast.jet.test.IgnoreInJenkinsOnWindows;
 import com.hazelcast.test.HazelcastSerialClassRunner;
 import com.hazelcast.test.annotation.ParallelJVMTest;
-import org.junit.Assume;
-import org.junit.BeforeClass;
 import org.junit.Rule;
 import org.junit.experimental.categories.Category;
 import org.junit.runner.RunWith;
@@ -51,13 +49,6 @@ public abstract class AbstractMySqlCdcIntegrationTest extends AbstractCdcIntegra
                     .withPassword("mysqlpw")
     );
 
-    @BeforeClass
-    public static void ignoreOnJdk15OrHigher() {
-        Assume.assumeFalse("https://github.com/hazelcast/hazelcast-jet/issues/2623, " +
-                        "https://github.com/hazelcast/hazelcast/issues/18800",
-                System.getProperty("java.version").matches("^1[56].*"));
-    }
-
     protected MySqlCdcSources.Builder sourceBuilder(String name) {
         return MySqlCdcSources.mysql(name)
                 .setDatabaseAddress(mysql.getHost())

extensions/cdc-mysql/src/test/java/com/hazelcast/jet/cdc/mysql/MySqlCdcNetworkIntegrationTest.java

@@ -37,8 +37,6 @@
 import eu.rekawek.toxiproxy.ToxiproxyClient;
 import eu.rekawek.toxiproxy.model.ToxicDirection;
 import org.junit.After;
-import org.junit.Assume;
-import org.junit.Before;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
 import org.junit.runner.RunWith;
@@ -101,13 +99,6 @@ public static Collection<Object[]> data() {
         });
     }
 
-    @Before
-    public void ignoreOnJdk15OrHigher() {
-        Assume.assumeFalse("https://github.com/hazelcast/hazelcast-jet/issues/2623, " +
-                        "https://github.com/hazelcast/hazelcast/issues/18800",
-                System.getProperty("java.version").matches("^1[567].*"));
-    }
-
     @After
     public void after() {
         if (mysql != null) {

hazelcast/src/main/java/com/hazelcast/jet/impl/pipeline/GrAggBuilder.java

@@ -106,9 +106,7 @@ public <A, R, OUT> BatchStage<OUT> buildBatch(
     public <A, R> StreamStage<KeyedWindowResult<K, R>> buildStream(@Nonnull AggregateOperation<A, ? extends R> aggrOp) {
         List<Transform> upstreamTransforms = toList(upstreamStages, s -> s.transform);
         FunctionAdapter fnAdapter = ADAPT_TO_JET_EVENT;
-        // Casts in this expression are a workaround for JDK 8 compiler bug:
-        @SuppressWarnings("unchecked")
-        List<FunctionEx<?, ? extends K>> adaptedKeyFns = toList(keyFns, fn -> fnAdapter.adaptKeyFn((FunctionEx) fn));
+        List<FunctionEx<?, ? extends K>> adaptedKeyFns = toList(keyFns, fnAdapter::adaptKeyFn);
         AbstractTransform transform = new WindowGroupTransform<K, R>(
                 upstreamTransforms, wDef, adaptedKeyFns, fnAdapter.adaptAggregateOperation(aggrOp));
         pipelineImpl.connect(upstreamStages, transform);

hazelcast/src/main/java/com/hazelcast/jet/pipeline/GeneralHashJoinBuilder.java

@@ -112,20 +112,19 @@ <R> GeneralStage<R> build0(BiFunctionEx<T0, ItemsByTag, R> mapToOutputFn) {
         List<Entry<Tag<?>, StageAndClause<?, T0, ?, ?>>> orderedClauses =
                 clauses.entrySet().stream()
                        .sorted(Entry.comparingByKey())
-                       .collect(toList());
+                       .toList();
         List<GeneralStage> upstream = concat(
                 Stream.of(stage0),
                 orderedClauses.stream().map(e -> e.getValue().stage())
         ).collect(toList());
-        Stream<? extends JoinClause<?, T0, ?, ?>> joinClauses = orderedClauses
+        Stream<JoinClause<?, T0, ?, ?>> joinClauses = orderedClauses
                 .stream()
                 .map(e -> e.getValue().clause());
         // JoinClause's second param, T0, is the same for all clauses but only
         // before FunctionAdapter treatment. After that it may be T0 or JetEvent<T0>
         // so we are forced to generalize to just ?.
-        // The (JoinClause) and (List<JoinClause>) casts are a workaround for JDK 8 compiler bugs.
-        List<JoinClause> adaptedClauses = (List<JoinClause>) joinClauses
-                .map(joinClause -> fnAdapter.adaptJoinClause((JoinClause) joinClause))
+        List<JoinClause> adaptedClauses = joinClauses
+                .map((JoinClause joinClause) -> fnAdapter.adaptJoinClause(joinClause))
                 .collect(toList());
         BiFunctionEx<?, ? super ItemsByTag, ?> adaptedOutputFn = fnAdapter.adaptHashJoinOutputFn(mapToOutputFn);
         // Here we break type safety and assume T0 as the type parameter even though