Switch to the new nested context API

Author: cescoffier

extensions/resteasy-reactive/rest-client/deployment/src/test/java/io/quarkus/rest/client/reactive/ContextLocalPropagationTest.java

@@ -110,10 +110,10 @@ private static Context determineRestClientContext() {
             // We will need a proper solution soon, but as we need to have a proper way to
             // set contextual information in Quarkus 3.20 (LTS), we can't risk breaking
             // client code everywhere, so for now we will tell people to check the context
-            Optional<Object> maybeParentContext = ContextLocals.get("__PARENT_CONTEXT__");
+            var maybeParentContext = ContextLocals.getParentContext();
             Context effectiveContext;
-            if (maybeParentContext.isPresent()) {
-                effectiveContext = (Context) maybeParentContext.get();
+            if (maybeParentContext != null) {
+                effectiveContext = maybeParentContext;
             } else {
                 effectiveContext = Vertx.currentContext();
             }

independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/ClientRequestContextImpl.java

@@ -65,19 +65,7 @@ public ClientRequestContextImpl(RestClientRequestContext restClientRequestContex
         // Always create a duplicated context because each REST Client invocation must have its own context
         // A separate context allows integrations like OTel to create a separate Span for each invocation (expected)
         Context current = client.vertx.getOrCreateContext();
-        this.context = VertxContext.createNewDuplicatedContext(current);
-        // If an interceptor wants to access the parent context, it can do so by using the "__PARENT_CONTEXT__" key.
-        // This approach is compatible with the next-to-be nested context support (from SmallRye Common).
-        // The "__PARENT_CONTEXT__" key will continue to reference the _parent_ context.
-        // So, currently, an interceptor needing to read from the original context will need to use:
-        // Context parent = ContextLocals.get("__PARENT_CONTEXT__");
-        // V v = parent.getLocal("some-key");
-        // To write to the original context, it will need to use:
-        // Context parent = ContextLocals.get("__PARENT_CONTEXT__");
-        // parent.putLocal("some-key", someValue);
-        // Note that unlike with nested contexts, multiple child contexts can write to the same parent key, and may
-        // lead to a race condition.
-        this.context.putLocal("__PARENT_CONTEXT__", current);
+        this.context = VertxContext.newNestedContext(current);
         restClientRequestContext.properties.put(VERTX_CONTEXT_PROPERTY, context);
     }