diff --git a/build.gradle b/build.gradle
index cc95ca83783..6fbe07535eb 100644
--- a/build.gradle
+++ b/build.gradle
@@ -750,7 +750,7 @@ class JDKDetails {
             url += "_${arch}"
         }
         println "Retrieving JDK from catalog..."
-        def catalogMetadataUrl = new URL(url)
+        def catalogMetadataUrl = URI.create(url).toURL()
         def catalogConnection = catalogMetadataUrl.openConnection()
         catalogConnection.requestMethod = 'GET'
         assert catalogConnection.responseCode == 200
diff --git a/logstash-core/lib/logstash/instrument/periodic_poller/jvm.rb b/logstash-core/lib/logstash/instrument/periodic_poller/jvm.rb
index 13d4db7053f..7b347cb831c 100644
--- a/logstash-core/lib/logstash/instrument/periodic_poller/jvm.rb
+++ b/logstash-core/lib/logstash/instrument/periodic_poller/jvm.rb
@@ -36,7 +36,7 @@ module LogStash module Instrument module PeriodicPoller
   class JVM < Base
     class GarbageCollectorName
       YOUNG_GC_NAMES = Set.new(["Copy", "PS Scavenge", "ParNew", "G1 Young Generation", "scavenge", "GPGC New"])
-      OLD_GC_NAMES = Set.new(["MarkSweepCompact", "PS MarkSweep", "ConcurrentMarkSweep", "G1 Old Generation", "global", "GPGC Old"])
+      OLD_GC_NAMES = Set.new(["MarkSweepCompact", "PS MarkSweep", "ConcurrentMarkSweep", "G1 Old Generation", "G1 Concurrent GC", "global", "GPGC Old"])
 
       YOUNG = :young
       OLD = :old
diff --git a/logstash-core/src/main/java/org/logstash/common/SourceWithMetadata.java b/logstash-core/src/main/java/org/logstash/common/SourceWithMetadata.java
index 1063dfd5830..0448a8140ea 100644
--- a/logstash-core/src/main/java/org/logstash/common/SourceWithMetadata.java
+++ b/logstash-core/src/main/java/org/logstash/common/SourceWithMetadata.java
@@ -65,6 +65,7 @@ public String getText() {
 
     private static final Pattern emptyString = Pattern.compile("^\\s*$");
 
+    @SuppressWarnings("this-escape")
     public SourceWithMetadata(String protocol, String id, Integer line, Integer column, String text, String metadata) throws IncompleteSourceWithMetadataException {
         this.protocol = protocol;
         this.id = id;
@@ -73,6 +74,9 @@ public SourceWithMetadata(String protocol, String id, Integer line, Integer colu
         this.text = text;
         this.metadata = metadata;
 
+        // This is the reason why of the "this-escape" suppress warning, a method (attributes) is invoked on
+        // a non completely initialized object and that could generate some errors in accessing fields.
+        // This is not the case because the method is private and not overridable in sub classes.
         List<Object> badAttributes = this.attributes().stream().filter(a -> {
             if (a == null) return true;
             if (a instanceof String) {
diff --git a/logstash-core/src/main/java/org/logstash/config/ir/expression/RegexValueExpression.java b/logstash-core/src/main/java/org/logstash/config/ir/expression/RegexValueExpression.java
index 6c1437ab2ef..3dd7889fc5c 100644
--- a/logstash-core/src/main/java/org/logstash/config/ir/expression/RegexValueExpression.java
+++ b/logstash-core/src/main/java/org/logstash/config/ir/expression/RegexValueExpression.java
@@ -34,7 +34,7 @@ public RegexValueExpression(SourceWithMetadata meta, Object value) throws Invali
             throw new InvalidIRException("Regex value expressions can only take strings!");
         }
 
-        this.regex = getSource();
+        this.regex = (String) value;
     }
 
     @Override
diff --git a/logstash-core/src/main/java/org/logstash/config/ir/graph/Edge.java b/logstash-core/src/main/java/org/logstash/config/ir/graph/Edge.java
index 4d5c17c6308..f72e7891e98 100644
--- a/logstash-core/src/main/java/org/logstash/config/ir/graph/Edge.java
+++ b/logstash-core/src/main/java/org/logstash/config/ir/graph/Edge.java
@@ -33,6 +33,7 @@ public abstract class Edge implements SourceComponent {
 
     private Graph graph;
 
+    @SuppressWarnings("this-escape")
     protected Edge(Vertex from, Vertex to) throws InvalidIRException {
         this.from = from;
         this.to = to;
@@ -41,6 +42,9 @@ protected Edge(Vertex from, Vertex to) throws InvalidIRException {
             throw new InvalidIRException("Cannot create a cyclic vertex! " + to);
         }
 
+        // This is the reason why of the "this-escape" suppress warning. The instance is passed to the method acceptsOutgoingEdge
+        // before the constructor completes, so could potentially reach some runtime errors due to fields not initialized.
+        // This is not the case because actually that method just does type check on reference.
         if (!this.from.acceptsOutgoingEdge(this)) {
             throw new Vertex.InvalidEdgeTypeException(String.format("Invalid outgoing edge %s for edge %s", this.from, this));
         }
diff --git a/logstash-core/src/main/java/org/logstash/execution/PipelineReporterExt.java b/logstash-core/src/main/java/org/logstash/execution/PipelineReporterExt.java
index 7c455253ec2..6ddc3eda5c3 100644
--- a/logstash-core/src/main/java/org/logstash/execution/PipelineReporterExt.java
+++ b/logstash-core/src/main/java/org/logstash/execution/PipelineReporterExt.java
@@ -157,7 +157,7 @@ public RubyHash toHash(final ThreadContext context) {
         return result;
     }
 
-    @SuppressWarnings({"unchecked","rawtypes"})
+    @SuppressWarnings({"unchecked", "rawtypes", "deprecation"})
     private RubyArray workerStates(final ThreadContext context, final RubyHash batchMap) {
         final RubyArray result = context.runtime.newArray();
         ((Iterable<IRubyObject>) pipeline.callMethod(context, "worker_threads"))
@@ -174,6 +174,7 @@ private RubyArray workerStates(final ThreadContext context, final RubyHash batch
 
                 IRubyObject batchSize = Optional.of((RubyThread) thread)
                         .map(RubyThread::getNativeThread)
+                        // JTODO getId has been deprecated in JDK 19, when JDK 21 is the target version use threadId() instead
                         .map(Thread::getId)
                         .map(id -> batchMap.op_aref(context, context.runtime.newFixnum(id)))
                         .map(batch -> extractBatchSize(context, batch))
diff --git a/logstash-core/src/main/java/org/logstash/execution/QueueReadClientBase.java b/logstash-core/src/main/java/org/logstash/execution/QueueReadClientBase.java
index d227adc8bd5..535cd838a0e 100644
--- a/logstash-core/src/main/java/org/logstash/execution/QueueReadClientBase.java
+++ b/logstash-core/src/main/java/org/logstash/execution/QueueReadClientBase.java
@@ -128,8 +128,10 @@ public IRubyObject rubyReadBatch(final ThreadContext context) throws Interrupted
     }
 
     @Override
+    @SuppressWarnings("deprecation")
     public void closeBatch(QueueBatch batch) throws IOException {
         batch.close();
+        // JTODO getId has been deprecated in JDK 19, when JDK 21 is the target version use threadId() instead
         inflightBatches.remove(Thread.currentThread().getId());
     }
 
@@ -186,7 +188,9 @@ public void rubyAddOutputMetrics(final IRubyObject size) {
     }
 
     @Override
+    @SuppressWarnings("deprecation")
     public void startMetrics(QueueBatch batch) {
+        // JTODO getId has been deprecated in JDK 19, when JDK 21 is the target version use threadId() instead
         long threadId = Thread.currentThread().getId();
         inflightBatches.put(threadId, batch);
     }
diff --git a/logstash-core/src/main/java/org/logstash/instrument/monitors/HotThreadsMonitor.java b/logstash-core/src/main/java/org/logstash/instrument/monitors/HotThreadsMonitor.java
index 0406d319597..e16aed00d7e 100644
--- a/logstash-core/src/main/java/org/logstash/instrument/monitors/HotThreadsMonitor.java
+++ b/logstash-core/src/main/java/org/logstash/instrument/monitors/HotThreadsMonitor.java
@@ -145,6 +145,7 @@ public static List<ThreadReport> detect() {
      *                      stacktrace_size - max depth of stack trace
      * @return A list of ThreadReport including all selected threads
      */
+    @SuppressWarnings("deprecation")
     public static List<ThreadReport> detect(Map<String, String> options) {
         String type = "cpu";
         if (options.containsKey(ORDERED_BY)) {
@@ -164,6 +165,7 @@ public static List<ThreadReport> detect(Map<String, String> options) {
         Map<Long, ThreadReport> reports = new HashMap<>();
 
         for (long threadId : threadMXBean.getAllThreadIds()) {
+            // JTODO getId has been deprecated in JDK 19, when JDK 21 is the target version use threadId() instead
             if (Thread.currentThread().getId() == threadId) {
                 continue;
             }
diff --git a/logstash-core/src/main/java/org/logstash/plugins/inputs/Stdin.java b/logstash-core/src/main/java/org/logstash/plugins/inputs/Stdin.java
index 5b2808a1919..017f36754b9 100644
--- a/logstash-core/src/main/java/org/logstash/plugins/inputs/Stdin.java
+++ b/logstash-core/src/main/java/org/logstash/plugins/inputs/Stdin.java
@@ -75,7 +75,10 @@ public Stdin(final String id, final Configuration configuration, final Context c
         this(id, configuration, context, new FileInputStream(FileDescriptor.in).getChannel());
     }
 
+    @SuppressWarnings("this-escape")
     Stdin(final String id, final Configuration configuration, final Context context, FileChannel inputChannel) {
+        // This is the reason why of the "this-escape" suppress warning, but this is used just to grab the class
+        // for the logger.
         logger = context.getLogger(this);
         this.id = id;
         try {
diff --git a/logstash-core/src/main/java/org/logstash/util/UtilExt.java b/logstash-core/src/main/java/org/logstash/util/UtilExt.java
index bba64002486..41b3825a4d0 100644
--- a/logstash-core/src/main/java/org/logstash/util/UtilExt.java
+++ b/logstash-core/src/main/java/org/logstash/util/UtilExt.java
@@ -34,6 +34,7 @@
 public class UtilExt {
 
     @JRubyMethod(module = true)
+    @SuppressWarnings("deprecation")
     public static IRubyObject get_thread_id(final ThreadContext context, IRubyObject self, IRubyObject thread) {
         if (!(thread instanceof RubyThread)) {
             throw context.runtime.newTypeError(thread, context.runtime.getThread());
@@ -41,6 +42,7 @@ public static IRubyObject get_thread_id(final ThreadContext context, IRubyObject
         final Thread javaThread = ((RubyThread) thread).getNativeThread(); // weak-reference
         // even if thread is dead the RubyThread instance might stick around while the Java thread
         // instance already could have been garbage collected - let's return nil for dead meat :
+        // JTODO getId has been deprecated in JDK 19, when JDK 21 is the target version use threadId() instead
         return javaThread == null ? context.nil : context.runtime.newFixnum(javaThread.getId());
     }
 
diff --git a/logstash-core/src/test/java/org/logstash/ext/JrubyMemoryReadClientExtTest.java b/logstash-core/src/test/java/org/logstash/ext/JrubyMemoryReadClientExtTest.java
index 0af4dfdcd39..dff3c4845a3 100644
--- a/logstash-core/src/test/java/org/logstash/ext/JrubyMemoryReadClientExtTest.java
+++ b/logstash-core/src/test/java/org/logstash/ext/JrubyMemoryReadClientExtTest.java
@@ -38,6 +38,7 @@
 public final class JrubyMemoryReadClientExtTest extends RubyTestBase {
 
     @Test
+    @SuppressWarnings("deprecation")
     public void testInflightBatchesTracking() throws InterruptedException, IOException {
         final BlockingQueue<JrubyEventExtLibrary.RubyEvent> queue =
             new ArrayBlockingQueue<>(10);
@@ -47,6 +48,7 @@ public void testInflightBatchesTracking() throws InterruptedException, IOExcepti
         final QueueBatch batch = client.readBatch();
         final RubyHash inflight = client.rubyGetInflightBatches(context);
         assertThat(inflight.size(), is(1));
+        // JTODO getId has been deprecated in JDK 19, when JDK 21 is the target version use threadId() instead
         assertThat(inflight.get(Thread.currentThread().getId()), is(batch));
         client.closeBatch(batch);
         assertThat(client.rubyGetInflightBatches(context).size(), is(0));
diff --git a/logstash-core/src/test/java/org/logstash/log/TestingDeprecationPlugin.java b/logstash-core/src/test/java/org/logstash/log/TestingDeprecationPlugin.java
index ee84b3b966d..cdaa85a9dfe 100644
--- a/logstash-core/src/test/java/org/logstash/log/TestingDeprecationPlugin.java
+++ b/logstash-core/src/test/java/org/logstash/log/TestingDeprecationPlugin.java
@@ -40,6 +40,7 @@ public class TestingDeprecationPlugin implements Codec {
      * @param configuration Logstash Configuration
      * @param context       Logstash Context
      */
+    @SuppressWarnings("this-escape")
     public TestingDeprecationPlugin(final Configuration configuration, final Context context) {
         deprecationLogger = context.getDeprecationLogger(this);
     }
diff --git a/logstash-core/src/test/java/org/logstash/plugins/AliasRegistryTest.java b/logstash-core/src/test/java/org/logstash/plugins/AliasRegistryTest.java
index 4ad12ed0060..2387bbb7c7b 100644
--- a/logstash-core/src/test/java/org/logstash/plugins/AliasRegistryTest.java
+++ b/logstash-core/src/test/java/org/logstash/plugins/AliasRegistryTest.java
@@ -6,6 +6,7 @@
 import java.io.IOException;
 import java.net.HttpURLConnection;
 import java.net.URL;
+import java.net.URI;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.Map;
@@ -34,7 +35,7 @@ public void testProductionConfigAliasesGemsExists() throws IOException {
 
         for (AliasRegistry.PluginCoordinate alias : aliasesDefinitions.keySet()) {
             final String gemName = alias.fullName();
-            URL url = new URL("https://rubygems.org/api/v1/gems/" + gemName +".json");
+            URL url = URI.create("https://rubygems.org/api/v1/gems/" + gemName +".json").toURL();
             HttpURLConnection connection = (HttpURLConnection) url.openConnection();
             connection.setRequestMethod("GET");
             connection.setRequestProperty("Accept", "application/json");
diff --git a/logstash-core/src/test/java/org/logstash/secret/store/SecretStoreFactoryTest.java b/logstash-core/src/test/java/org/logstash/secret/store/SecretStoreFactoryTest.java
index ab9f6ea3c7b..9a6129375bc 100644
--- a/logstash-core/src/test/java/org/logstash/secret/store/SecretStoreFactoryTest.java
+++ b/logstash-core/src/test/java/org/logstash/secret/store/SecretStoreFactoryTest.java
@@ -157,6 +157,7 @@ public static class MemoryStore implements SecretStore {
 
         Map<SecretIdentifier, ByteBuffer> secrets = new HashMap(1);
 
+        @SuppressWarnings("this-escape")
         public MemoryStore() {
             persistSecret(LOGSTASH_MARKER, LOGSTASH_MARKER.getKey().getBytes(StandardCharsets.UTF_8));
         }