Generated application.properties.example doesn't include CORS property
**Describe the bug**

When generating an example application.properties files the `quarkus.http.cors` entry is missing. The other cors related entries are present as expected (i.e. `quarkus.http.cors.exposed-headers`).

**Expected behavior**

I would expect the example file to include all the available possible properties, including `quarkus.http.cors` along-side a relative comment.

**Actual behavior**

The `quarkus.http.cors` entry is not present

**To Reproduce**
Steps to reproduce the behavior:
1. Create a quarkus project `mvn io.quarkus:quarkus-maven-plugin:0.19.1:create` with the default values (or use an existing one)
2. From within the project `cd my-quarkus-project/` generate an `application.properties.example` file `./mvnw quarkus:generate-config`
3. Check the created file `src/main/resources/application.properties.example` for the missing entry. There is not a `quarkus.http.cors` present. The other cors related entries are present:

```bash
grep 'cors' src/main/resources/application.properties.example 
#quarkus.http.cors.exposed-headers=
#quarkus.http.cors.headers=
#quarkus.http.cors.methods=
#quarkus.http.cors.origins=
```

**Environment:**
 - Quarkus version or git rev: reproduced on quarkus 0.18, 0.19 and 0.19.1
 - Maven version: `Apache Maven 3.6.0 (97c98ec64a1fdfee7767ce5ffb20918da4f719f3; 2018-10-24T21:41:47+03:00)`
 - Maven wrapped version: `Apache Maven 3.6.1 (d66c9c0b3152b2e69ee9bac180bb8fcc8e6af555; 2019-04-04T22:00:29+03:00)`
diff --git a/core/creator/src/main/java/io/quarkus/creator/phase/generateconfig/GenerateConfigPhase.java b/core/creator/src/main/java/io/quarkus/creator/phase/generateconfig/GenerateConfigPhase.java
index 19f5f5cdfd0..7ac54ba30b4 100644
--- a/core/creator/src/main/java/io/quarkus/creator/phase/generateconfig/GenerateConfigPhase.java
+++ b/core/creator/src/main/java/io/quarkus/creator/phase/generateconfig/GenerateConfigPhase.java
@@ -118,7 +118,6 @@ private void doProcess(CurateOutcome appState) throws AppCreatorException {
             runnerClassLoader = new URLClassLoader(cpUrls.toArray(new URL[cpUrls.size()]), getClass().getClassLoader());
 
             ClassLoader old = Thread.currentThread().getContextClassLoader();
-            BuildResult result;
             try {
                 Thread.currentThread().setContextClassLoader(runnerClassLoader);
 
diff --git a/core/deployment/src/main/java/io/quarkus/deployment/steps/ConfigDescriptionBuildStep.java b/core/deployment/src/main/java/io/quarkus/deployment/steps/ConfigDescriptionBuildStep.java
index 4a273b512bb..c2cb9e9da1a 100644
--- a/core/deployment/src/main/java/io/quarkus/deployment/steps/ConfigDescriptionBuildStep.java
+++ b/core/deployment/src/main/java/io/quarkus/deployment/steps/ConfigDescriptionBuildStep.java
@@ -10,6 +10,7 @@
 
 import io.quarkus.deployment.annotations.BuildStep;
 import io.quarkus.deployment.builditem.BuildTimeConfigurationBuildItem;
+import io.quarkus.deployment.builditem.BuildTimeRunTimeFixedConfigurationBuildItem;
 import io.quarkus.deployment.builditem.ConfigDescriptionBuildItem;
 import io.quarkus.deployment.builditem.RunTimeConfigurationBuildItem;
 import io.quarkus.deployment.configuration.ConfigDefinition;
@@ -20,7 +21,8 @@ public class ConfigDescriptionBuildStep {
     @BuildStep
     List<ConfigDescriptionBuildItem> createConfigDescriptions(
             RunTimeConfigurationBuildItem runtimeConfig,
-            BuildTimeConfigurationBuildItem buildTimeConfig) throws Exception {
+            BuildTimeConfigurationBuildItem buildTimeConfig,
+            BuildTimeRunTimeFixedConfigurationBuildItem buildTimeRuntimeConfig) throws Exception {
         Properties javadoc = new Properties();
         Enumeration<URL> resources = Thread.currentThread().getContextClassLoader()
                 .getResources("META-INF/quarkus-javadoc.properties");
@@ -32,6 +34,7 @@ List<ConfigDescriptionBuildItem> createConfigDescriptions(
         List<ConfigDescriptionBuildItem> ret = new ArrayList<>();
         processConfig(runtimeConfig.getConfigDefinition(), ret, javadoc);
         processConfig(buildTimeConfig.getConfigDefinition(), ret, javadoc);
+        processConfig(buildTimeRuntimeConfig.getConfigDefinition(), ret, javadoc);
         return ret;
     }
 
diff --git a/extensions/undertow/runtime/src/main/java/io/quarkus/undertow/runtime/HttpBuildConfig.java b/extensions/undertow/runtime/src/main/java/io/quarkus/undertow/runtime/HttpBuildConfig.java
index b399b4c329d..b3685ca5dd7 100644
--- a/extensions/undertow/runtime/src/main/java/io/quarkus/undertow/runtime/HttpBuildConfig.java
+++ b/extensions/undertow/runtime/src/main/java/io/quarkus/undertow/runtime/HttpBuildConfig.java
@@ -11,7 +11,7 @@
 public class HttpBuildConfig {
 
     /**
-     * The CORS config
+     * Enable the CORS filter.
      */
     @ConfigItem(name = "cors")
     public boolean corsEnabled = false;
['core/creator/src/main/java/io/quarkus/creator/phase/generateconfig/GenerateConfigPhase.java', 'core/deployment/src/main/java/io/quarkus/deployment/steps/ConfigDescriptionBuildStep.java', 'extensions/undertow/runtime/src/main/java/io/quarkus/undertow/runtime/HttpBuildConfig.java']