Fix order of defaults recording

core/deployment/src/main/java/io/quarkus/deployment/steps/ConfigGenerationBuildStep.java

@@ -199,11 +199,11 @@ void generateBuilders(
             BuildProducer<GeneratedClassBuildItem> generatedClass,
             BuildProducer<ReflectiveClassBuildItem> reflectiveClass) throws Exception {
 
-        // Default Values collected from mappings / roots and build item
-        Map<String, String> defaultValues = new HashMap<>(configItem.getReadResult().getRunTimeDefaultValues());
+        Map<String, String> defaultValues = new HashMap<>();
         for (RunTimeConfigurationDefaultBuildItem e : runTimeDefaults) {
             defaultValues.put(e.getKey(), e.getValue());
         }
+        defaultValues.putAll(configItem.getReadResult().getRunTimeDefaultValues());
 
         Set<String> converters = discoverService(Converter.class, reflectiveClass);
         Set<String> interceptors = discoverService(ConfigSourceInterceptor.class, reflectiveClass);

integration-tests/test-extension/extension/deployment/src/main/java/io/quarkus/extest/deployment/BuildTimeCustomConfigBuilder.java

@@ -9,7 +9,11 @@
 public class BuildTimeCustomConfigBuilder implements SmallRyeConfigBuilderCustomizer {
     @Override
     public void configBuilder(final SmallRyeConfigBuilder builder) {
+        // for ConfigBuilderTest
         builder.withSources(
                 new PropertiesConfigSource(Map.of("prop.recorded.from.btconfigsource", "1234"), "BuildTimeConfigSource", 100));
+        // for RecorderRuntimeConfigTest
+        builder.withSources(
+                new PropertiesConfigSource(Map.of("recorded.property", "from-application"), "BuildTimeConfigSource", 250));
     }
 }

integration-tests/test-extension/extension/deployment/src/main/java/io/quarkus/extest/deployment/TestProcessor.java

@@ -42,6 +42,7 @@
 import io.quarkus.deployment.builditem.LogHandlerBuildItem;
 import io.quarkus.deployment.builditem.ObjectSubstitutionBuildItem;
 import io.quarkus.deployment.builditem.RunTimeConfigBuilderBuildItem;
+import io.quarkus.deployment.builditem.RunTimeConfigurationDefaultBuildItem;
 import io.quarkus.deployment.builditem.ServiceStartBuildItem;
 import io.quarkus.deployment.builditem.ShutdownContextBuildItem;
 import io.quarkus.deployment.builditem.StaticInitConfigBuilderBuildItem;
@@ -486,6 +487,11 @@ void neverRunThisOne() {
         throw new IllegalStateException("Not supposed to run!");
     }
 
+    @BuildStep
+    void recordProperty(BuildProducer<RunTimeConfigurationDefaultBuildItem> runTimeConfigurationDefault) {
+        runTimeConfigurationDefault.produce(new RunTimeConfigurationDefaultBuildItem("recorded.property", "from-build-step"));
+    }
+
     public static final class Never implements BooleanSupplier {
         TestBuildTimeConfig config;
 

integration-tests/test-extension/extension/deployment/src/test/java/io/quarkus/config/RecorderRuntimeConfigTest.java

@@ -0,0 +1,27 @@
+package io.quarkus.config;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import jakarta.inject.Inject;
+
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusUnitTest;
+import io.smallrye.config.SmallRyeConfig;
+
+public class RecorderRuntimeConfigTest {
+    @RegisterExtension
+    static final QuarkusUnitTest TEST = new QuarkusUnitTest()
+            .setArchiveProducer(() -> ShrinkWrap.create(JavaArchive.class));
+
+    @Inject
+    SmallRyeConfig config;
+
+    @Test
+    void runtimeConfig() {
+        assertEquals("from-application", config.getRawValue("recorded.property"));
+    }
+}