Merge pull request #8318 from stuartwdouglas/8301

Don't remove classes from the resettable elements

independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/classloading/MemoryClassPathElement.java

@@ -10,6 +10,7 @@
 import java.security.CodeSource;
 import java.security.ProtectionDomain;
 import java.security.cert.Certificate;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
 
@@ -22,7 +23,21 @@ public MemoryClassPathElement(Map<String, byte[]> resources) {
     }
 
     public void reset(Map<String, byte[]> resources) {
-        this.resources = resources;
+        Map<String, byte[]> newResources = new HashMap<>(resources);
+        //we can't delete .class files from the loader
+        //gizmo may not generate the same function names on restart
+        //so if we delete them already loaded classes may have problems, as functions they reference
+        //may have been removed
+        //see https://github.com/quarkusio/quarkus/issues/8301
+        for (Map.Entry<String, byte[]> e : this.resources.entrySet()) {
+            if (newResources.containsKey(e.getKey())) {
+                continue;
+            }
+            if (e.getKey().endsWith(".class")) {
+                newResources.put(e.getKey(), e.getValue());
+            }
+        }
+        this.resources = newResources;
     }
 
     @Override