Ensure ParameterConverter is loaded from the TCCL

This is needed because otherwise dev-mode could break
in some cases

Fixes: quarkusio#39777
Follows up on: quarkusio#39691

independent-projects/resteasy-reactive/server/processor/src/main/java/org/jboss/resteasy/reactive/server/processor/scanning/ClassInjectorTransformer.java

@@ -36,6 +36,7 @@
 import org.jboss.resteasy.reactive.server.core.parameters.converters.DelegatingParameterConverterSupplier;
 import org.jboss.resteasy.reactive.server.core.parameters.converters.ParameterConverter;
 import org.jboss.resteasy.reactive.server.core.parameters.converters.ParameterConverterSupplier;
+import org.jboss.resteasy.reactive.server.core.parameters.converters.ParameterConverterSupport;
 import org.jboss.resteasy.reactive.server.core.parameters.converters.RuntimeResolvedConverter;
 import org.jboss.resteasy.reactive.server.injection.ResteasyReactiveInjectionContext;
 import org.jboss.resteasy.reactive.server.injection.ResteasyReactiveInjectionTarget;
@@ -77,6 +78,9 @@ public class ClassInjectorTransformer implements BiFunction<String, ClassVisitor
     private static final String INIT_CONVERTER_FIELD_NAME = "__quarkus_converter__";
     private static final String INIT_CONVERTER_METHOD_DESCRIPTOR = "(" + QUARKUS_REST_DEPLOYMENT_DESCRIPTOR + ")V";
 
+    private static final String PARAMETER_CONVERTER_SUPPORT_BINARY_NAME = ParameterConverterSupport.class.getName().replace('.',
+            '/');
+
     private static final String MULTIPART_SUPPORT_BINARY_NAME = MultipartSupport.class.getName().replace('.', '/');
 
     private static final String OBJECT_BINARY_NAME = Object.class.getName().replace('.', '/');
@@ -457,18 +461,14 @@ private void generateConverterInitMethod(FieldInfo fieldInfo, ParameterConverter
                 initConverterMethod.visitJumpInsn(Opcodes.IFNONNULL, notNull);
                 // stack: [converter]
                 initConverterMethod.visitInsn(Opcodes.POP);
-                // stack: []
-                // let's instantiate our delegate
-                initConverterMethod.visitTypeInsn(Opcodes.NEW, delegateBinaryName);
-                // stack: [converter]
-                initConverterMethod.visitInsn(Opcodes.DUP);
-                // stack: [converter, converter]
-                initConverterMethod.visitMethodInsn(Opcodes.INVOKESPECIAL, delegateBinaryName, "<init>",
-                        "()V", false);
-                // stack: [converter]
-                // If we don't cast this to ParameterConverter, ASM in computeFrames will call getCommonSuperType
-                // and try to load our generated class before we can load it, so we insert this cast to avoid that
-                initConverterMethod.visitTypeInsn(Opcodes.CHECKCAST, PARAMETER_CONVERTER_BINARY_NAME);
+
+                // className param
+                initConverterMethod.visitLdcInsn(delegateBinaryName.replace('/', '.'));
+                initConverterMethod.visitMethodInsn(Opcodes.INVOKESTATIC, PARAMETER_CONVERTER_SUPPORT_BINARY_NAME,
+                        "create",
+                        "(" + STRING_DESCRIPTOR + ")" + PARAMETER_CONVERTER_DESCRIPTOR,
+                        false);
+
                 // end default delegate
                 initConverterMethod.visitLabel(notNull);
             }

independent-projects/resteasy-reactive/server/runtime/src/main/java/org/jboss/resteasy/reactive/server/core/parameters/converters/ParameterConverterSupport.java

@@ -0,0 +1,25 @@
+package org.jboss.resteasy.reactive.server.core.parameters.converters;
+
+/**
+ * This class isn't used directly, it is however used by generated code meant to deal with {@link ParameterConverter}.
+ */
+@SuppressWarnings("unused")
+public final class ParameterConverterSupport {
+
+    private ParameterConverterSupport() {
+    }
+
+    /**
+     * Normally the reflective instantiation would not be needed, and we could just instantiate normally,
+     * however that could break dev-mode when the converters are in a different module and non-standard Maven
+     * configuration is used (see <a href="https://github.com/quarkusio/quarkus/issues/39773#issuecomment-2030493539">this</a>)
+     */
+    public static ParameterConverter create(String className) {
+        try {
+            Class<?> clazz = Class.forName(className, true, Thread.currentThread().getContextClassLoader());
+            return (ParameterConverter) clazz.getConstructor().newInstance();
+        } catch (Exception e) {
+            throw new RuntimeException("Unable to create instance of " + className, e);
+        }
+    }
+}