Fixing issue whereby nested annotations weren't being handled because…

… the derived class name was incorrect.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=297413484

core/src/main/java/com/google/errorprone/refaster/UTemplater.java

@@ -116,7 +116,7 @@
 import java.util.Map;
 import javax.annotation.Nullable;
 import javax.lang.model.element.Element;
-import javax.lang.model.element.Name;
+import javax.lang.model.element.ElementKind;
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.type.DeclaredType;
 import javax.lang.model.type.MirroredTypeException;
@@ -919,11 +919,11 @@ public UForAll visitForAll(ForAll type, Void v) {
   public static ImmutableClassToInstanceMap<Annotation> annotationMap(Symbol symbol) {
     ImmutableClassToInstanceMap.Builder<Annotation> builder = ImmutableClassToInstanceMap.builder();
     for (Compound compound : symbol.getAnnotationMirrors()) {
-      Name qualifiedAnnotationType =
-          ((TypeElement) compound.getAnnotationType().asElement()).getQualifiedName();
+      String annotationClassName =
+          classNameFrom((TypeElement) compound.getAnnotationType().asElement());
       try {
         Class<? extends Annotation> annotationClazz =
-            Class.forName(qualifiedAnnotationType.toString()).asSubclass(Annotation.class);
+            Class.forName(annotationClassName).asSubclass(Annotation.class);
         builder.put(
             (Class) annotationClazz,
             AnnotationProxyMaker.generateAnnotation(compound, annotationClazz));
@@ -933,4 +933,19 @@ public static ImmutableClassToInstanceMap<Annotation> annotationMap(Symbol symbo
     }
     return builder.build();
   }
+
+  // Class.forName() needs nested classes as "foo.Bar$Baz$Quux", not "foo.Bar.Baz.Quux"
+  // (which is what getQualifiedName() returns).
+  private static String classNameFrom(TypeElement type) {
+    // Get the full type name (e.g. "foo.Bar.Baz.Quux") before walking up the hierarchy.
+    String typeName = type.getQualifiedName().toString();
+    // Find outermost enclosing type (e.g. "foo.Bar" in our example), possibly several levels up.
+    // Packages enclose types, so we cannot just wait until we hit null.
+    while (type.getEnclosingElement().getKind() == ElementKind.CLASS) {
+      type = (TypeElement) type.getEnclosingElement();
+    }
+    // Start with outermost class name and append remainder of full type name with '.' -> '$'
+    String className = type.getQualifiedName().toString();
+    return className + typeName.substring(className.length()).replace('.', '$');
+  }
 }