Make room for laziness in the Annotations interface

core/descriptors/src/org/jetbrains/jet/lang/descriptors/annotations/Annotations.java

@@ -17,28 +17,23 @@
 package org.jetbrains.jet.lang.descriptors.annotations;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.ReadOnly;
 
 import java.util.Collections;
 import java.util.Iterator;
-import java.util.List;
 
 public interface Annotations extends Iterable<AnnotationDescriptor> {
     Annotations EMPTY = new Annotations() {
-        @NotNull
         @Override
-        public List<AnnotationDescriptor> getAnnotationDescriptors() {
-            return Collections.emptyList();
+        public boolean isEmpty() {
+            return true;
         }
 
         @NotNull
         @Override
         public Iterator<AnnotationDescriptor> iterator() {
-            return getAnnotationDescriptors().iterator();
+            return Collections.<AnnotationDescriptor>emptyList().iterator();
         }
     };
 
-    @NotNull
-    @ReadOnly
-    List<AnnotationDescriptor> getAnnotationDescriptors();
+    boolean isEmpty();
 }

core/descriptors/src/org/jetbrains/jet/lang/descriptors/annotations/AnnotationsImpl.java

@@ -29,11 +29,15 @@ public class AnnotationsImpl implements Annotations {
     }
 
     @NotNull
-    @Override
     public List<AnnotationDescriptor> getAnnotationDescriptors() {
         return annotations;
     }
 
+    @Override
+    public boolean isEmpty() {
+        return getAnnotationDescriptors().isEmpty();
+    }
+
     @NotNull
     @Override
     public Iterator<AnnotationDescriptor> iterator() {

core/descriptors/src/org/jetbrains/jet/lang/descriptors/impl/MutableClassDescriptorLite.java

@@ -39,7 +39,7 @@ import java.util.List;
 
 public abstract class MutableClassDescriptorLite extends ClassDescriptorBase {
 
-    private Annotations annotations = new AnnotationsImpl(new ArrayList<AnnotationDescriptor>(0));
+    private Annotations annotations;
 
     private List<TypeParameterDescriptor> typeParameters;
     private Collection<JetType> supertypes = Lists.newArrayList();
@@ -183,6 +183,9 @@ public abstract class MutableClassDescriptorLite extends ClassDescriptorBase {
     @NotNull
     @Override
     public Annotations getAnnotations() {
+        if (annotations == null) {
+            annotations = new AnnotationsImpl(new ArrayList<AnnotationDescriptor>(0));
+        }
         return annotations;
     }
 
@@ -190,8 +193,12 @@ public abstract class MutableClassDescriptorLite extends ClassDescriptorBase {
         this.annotations = annotations;
     }
 
-    public void addAnnotations(@NotNull List<AnnotationDescriptor> annotationDescriptors) {
-        this.annotations.getAnnotationDescriptors().addAll(annotationDescriptors);
+    public void addAnnotations(@NotNull Iterable<AnnotationDescriptor> annotationDescriptors) {
+
+        AnnotationsImpl annotationsImpl = (AnnotationsImpl) getAnnotations();
+        for (AnnotationDescriptor annotationDescriptor : annotationDescriptors) {
+            annotationsImpl.getAnnotationDescriptors().add(annotationDescriptor);
+        }
     }
 
     private PackageLikeBuilder builder = null;