Ignore config_ordinal for default values source

core/deployment/src/main/java/io/quarkus/deployment/configuration/BuildTimeConfigurationReader.java

@@ -24,6 +24,7 @@
 import java.util.TreeMap;
 
 import org.eclipse.microprofile.config.inject.ConfigProperty;
+import org.eclipse.microprofile.config.spi.ConfigSource;
 import org.eclipse.microprofile.config.spi.Converter;
 import org.jboss.logging.Logger;
 import org.wildfly.common.Assert;
@@ -296,6 +297,10 @@ ReadResult run() {
             }
             // sweep-up
             for (String propertyName : config.getPropertyNames()) {
+                if (propertyName.equals(ConfigSource.CONFIG_ORDINAL)) {
+                    continue;
+                }
+
                 NameIterator ni = new NameIterator(propertyName);
                 if (ni.hasNext() && ni.nextSegmentEquals("quarkus")) {
                     ni.next();

extensions/arc/deployment/src/test/java/io/quarkus/arc/test/config/ConfigDefaultValues.java

@@ -0,0 +1,49 @@
+package io.quarkus.arc.test.config;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import javax.inject.Inject;
+
+import org.eclipse.microprofile.config.Config;
+import org.eclipse.microprofile.config.spi.ConfigSource;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.asset.StringAsset;
+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;
+
+public class ConfigDefaultValues {
+    @RegisterExtension
+    static final QuarkusUnitTest TEST = new QuarkusUnitTest()
+            .setArchiveProducer(() -> ShrinkWrap.create(JavaArchive.class)
+                    .addAsResource(new StringAsset("config_ordinal=1000\n" +
+                            "my.prop=1234\n"), "application.properties"));
+    @Inject
+    Config config;
+
+    @Test
+    void configDefaultValues() {
+        ConfigSource defaultValues = getConfigSourceByName("PropertiesConfigSource[source=Specified default values]");
+        assertNotNull(defaultValues);
+        assertEquals(Integer.MIN_VALUE + 100, defaultValues.getOrdinal());
+
+        ConfigSource applicationProperties = getConfigSourceByName("PropertiesConfigSource[source=application.properties]");
+        assertNotNull(applicationProperties);
+        assertEquals(1000, applicationProperties.getOrdinal());
+
+        assertEquals("1234", defaultValues.getValue("my.prop"));
+        assertEquals("1234", applicationProperties.getValue("my.prop"));
+    }
+
+    private ConfigSource getConfigSourceByName(String name) {
+        for (ConfigSource configSource : config.getConfigSources()) {
+            if (configSource.getName().contains(name)) {
+                return configSource;
+            }
+        }
+        return null;
+    }
+}