eliminated use of Java 14 instanceof pattern matching (#233)

Author: oertl

jfr-streaming/src/main/java/io/opentelemetry/contrib/jfr/metrics/internal/ThreadGrouper.java

@@ -13,7 +13,8 @@ public final class ThreadGrouper {
   // FIXME doesn't actually do any grouping, but should be safe for now
   public Optional<String> groupedName(RecordedEvent ev) {
     Object thisField = ev.getValue("eventThread");
-    if (thisField instanceof RecordedThread thread) {
+    if (thisField instanceof RecordedThread) {
+      RecordedThread thread = (RecordedThread) thisField;
       return Optional.of(thread.getJavaName());
     }
     return Optional.empty();

jfr-streaming/src/main/java/io/opentelemetry/contrib/jfr/metrics/internal/memory/GCHeapSummaryHandler.java

@@ -108,7 +108,9 @@ private void recordValues(RecordedEvent before, RecordedEvent after) {
       memoryHistogram.record(after.getLong(HEAP_USED), ATTR_MEMORY_USED);
     }
     if (after.hasField(HEAP_SPACE)) {
-      if (after.getValue(HEAP_SPACE) instanceof RecordedObject heapSpace) {
+      Object heapSpaceValue = after.getValue(HEAP_SPACE);
+      if (heapSpaceValue instanceof RecordedObject) {
+        RecordedObject heapSpace = (RecordedObject) heapSpaceValue;
         if (heapSpace.hasField(COMMITTED_SIZE)) {
           memoryHistogram.record(heapSpace.getLong(COMMITTED_SIZE), ATTR_MEMORY_COMMITTED);
         }

jfr-streaming/src/main/java/io/opentelemetry/contrib/jfr/metrics/internal/memory/ParallelHeapSummaryHandler.java

@@ -100,21 +100,31 @@ public void accept(RecordedEvent ev) {
   }
 
   private void recordValues(RecordedEvent before, RecordedEvent after) {
-    if (after.hasField("edenSpace")
-        && after.getValue("edenSpace") instanceof RecordedObject edenSpace) {
-      memoryHistogram.record(edenSpace.getLong("size"), ATTR_MEMORY_EDEN_SIZE);
-      if (before.hasField("edenSpace")
-          && before.getValue("edenSpace") instanceof RecordedObject beforeSpace) {
-        if (edenSpace.hasField("size") && beforeSpace.hasField("size")) {
-          memoryHistogram.record(
-              edenSpace.getLong("size") - beforeSpace.getLong("size"), ATTR_MEMORY_EDEN_SIZE_DELTA);
+    if (after.hasField("edenSpace")) {
+      Object edenSpaceObj = after.getValue("edenSpace");
+      if (edenSpaceObj instanceof RecordedObject) {
+        RecordedObject edenSpace = (RecordedObject) edenSpaceObj;
+        memoryHistogram.record(edenSpace.getLong("size"), ATTR_MEMORY_EDEN_SIZE);
+        if (before.hasField("edenSpace")) {
+          Object beforeSpaceObj = before.getValue("edenSpace");
+          if (beforeSpaceObj instanceof RecordedObject) {
+            RecordedObject beforeSpace = (RecordedObject) beforeSpaceObj;
+            if (edenSpace.hasField("size") && beforeSpace.hasField("size")) {
+              memoryHistogram.record(
+                  edenSpace.getLong("size") - beforeSpace.getLong("size"),
+                  ATTR_MEMORY_EDEN_SIZE_DELTA);
+            }
+          }
         }
       }
     }
-    if (after.hasField("fromSpace")
-        && after.getValue("fromSpace") instanceof RecordedObject fromSpace) {
-      if (fromSpace.hasField("size")) {
-        memoryHistogram.record(fromSpace.getLong("size"), ATTR_MEMORY_SURVIVOR_SIZE);
+    if (after.hasField("fromSpace")) {
+      Object fromSpaceObj = after.getValue("fromSpace");
+      if (after.getValue("fromSpace") instanceof RecordedObject) {
+        RecordedObject fromSpace = (RecordedObject) fromSpaceObj;
+        if (fromSpace.hasField("size")) {
+          memoryHistogram.record(fromSpace.getLong("size"), ATTR_MEMORY_SURVIVOR_SIZE);
+        }
       }
     }
   }