Cleanup on live reload also removes generated classes
**Describe the bug**
Generated classes are removed during live reload.

**Expected behavior**
Generated classes are not deleted.

**To Reproduce**
Steps to reproduce the behavior:
1. `git clone https://github.com/antoniomacri/quarkus-rocker-class-cleanup.git`
2. `mvn install`
3. `ll target/classes/views` ->  `HostingPage.class`
4. `mvn quarkus:dev` (+ `mvn install` + F5 on `http://localhost:8080/`)
5. `ll target/classes/views` ->  `HostingPage.class` deleted

**Environment:**
 - Output of `java -version`: 1.8
 - Quarkus version or git rev: 0.20.0

diff --git a/core/devmode/src/main/java/io/quarkus/dev/RuntimeUpdatesProcessor.java b/core/devmode/src/main/java/io/quarkus/dev/RuntimeUpdatesProcessor.java
index 064b89633b2..65280e047e2 100644
--- a/core/devmode/src/main/java/io/quarkus/dev/RuntimeUpdatesProcessor.java
+++ b/core/devmode/src/main/java/io/quarkus/dev/RuntimeUpdatesProcessor.java
@@ -202,12 +202,8 @@ private boolean checkForClassFilesChangesInModule(DevModeContext.ModuleInfo modu
                 for (Path classFilePath : classFilePaths) {
                     final Path sourceFilePath = retrieveSourceFilePathForClassFile(classFilePath, moduleChangedSourceFiles,
                             module);
-                    if (sourceFilePath == null) {
-                        Files.deleteIfExists(classFilePath);
-                        classFilePathToSourceFilePath.remove(classFilePath);
-                        hasChanges = true;
-                    } else {
-                        final long classFileModificationTime = Files.getLastModifiedTime(classFilePath).toMillis();
+                    final long classFileModificationTime = Files.getLastModifiedTime(classFilePath).toMillis();
+                    if (sourceFilePath != null) {
                         if (Files.notExists(sourceFilePath)) {
                             // Source file has been deleted. Delete class and restart
                             Files.deleteIfExists(classFilePath);
@@ -226,6 +222,8 @@ private boolean checkForClassFilesChangesInModule(DevModeContext.ModuleInfo modu
                                 hasChanges = true;
                             }
                         }
+                    } else if (classFileModificationTime > lastChange) {
+                        hasChanges = true;
                     }
                 }
             }
['core/devmode/src/main/java/io/quarkus/dev/RuntimeUpdatesProcessor.java']