Index: lucene/benchmark/src/java/org/apache/lucene/benchmark/byTask/feeds/DocMaker.java
===================================================================
--- lucene/benchmark/src/java/org/apache/lucene/benchmark/byTask/feeds/DocMaker.java	(revision 1371227)
+++ lucene/benchmark/src/java/org/apache/lucene/benchmark/byTask/feeds/DocMaker.java	(working copy)
@@ -226,7 +226,7 @@
 
     final DocState ds = getDocState();
     final Document doc = reuseFields ? ds.doc : new Document();
-    doc.getFields().clear();
+    doc.clear();
     
     // Set ID_FIELD
     FieldType ft = new FieldType(valType);
Index: lucene/benchmark/src/java/org/apache/lucene/benchmark/byTask/tasks/ReadTokensTask.java
===================================================================
--- lucene/benchmark/src/java/org/apache/lucene/benchmark/byTask/tasks/ReadTokensTask.java	(revision 1371227)
+++ lucene/benchmark/src/java/org/apache/lucene/benchmark/byTask/tasks/ReadTokensTask.java	(working copy)
@@ -26,6 +26,7 @@
 import org.apache.lucene.benchmark.byTask.PerfRunData;
 import org.apache.lucene.benchmark.byTask.feeds.DocMaker;
 import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
 import org.apache.lucene.document.IntField;
 import org.apache.lucene.document.LongField;
 import org.apache.lucene.document.FloatField;
@@ -68,7 +69,7 @@
 
   @Override
   public int doLogic() throws Exception {
-    List<IndexableField> fields = doc.getFields();
+    List<Field> fields = doc.getFields();
     Analyzer analyzer = getRunData().getAnalyzer();
     int tokenCount = 0;
     for(final IndexableField field : fields) {
Index: lucene/core/src/java/org/apache/lucene/document/Document.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/document/Document.java	(revision 1371227)
+++ lucene/core/src/java/org/apache/lucene/document/Document.java	(working copy)
@@ -184,15 +184,15 @@
    * @param name the name of the field
    * @return a <code>Fieldable[]</code> array
    */
-  public IndexableField[] getFields(String name) {
-    List<IndexableField> result = new ArrayList<IndexableField>();
-    for (IndexableField field : fields) {
+  public Field[] getFields(String name) {
+    List<Field> result = new ArrayList<Field>();
+    for (Field field : fields) {
       if (field.name().equals(name)) {
         result.add(field);
       }
     }
 
-    return result.toArray(new IndexableField[result.size()]);
+    return result.toArray(new Field[result.size()]);
   }
   
   /** Returns a List of all the fields in a document.
@@ -201,13 +201,8 @@
    * index, e.g. {@link IndexSearcher#doc(int)} or {@link
    * IndexReader#document(int)}.
    */
-  public final List<IndexableField> getFields() {
-    List<IndexableField> result = new ArrayList<IndexableField>();
-    for (IndexableField field : fields) {
-      result.add(field);
-    }
-
-    return result;
+  public final List<Field> getFields() {
+    return Collections.unmodifiableList(fields);
   }
   
    private final static String[] NO_STRINGS = new String[0];
@@ -316,4 +311,8 @@
       }
     };
   }
+
+  public void clear() {
+    fields.clear();
+  }
 }
Index: lucene/core/src/test/org/apache/lucene/document/TestDocument.java
===================================================================
--- lucene/core/src/test/org/apache/lucene/document/TestDocument.java	(revision 1371227)
+++ lucene/core/src/test/org/apache/lucene/document/TestDocument.java	(working copy)
@@ -18,6 +18,7 @@
  */
 
 import java.io.StringReader;
+import java.util.List;
 
 import org.apache.lucene.analysis.EmptyTokenizer;
 import org.apache.lucene.analysis.MockAnalyzer;
@@ -124,7 +125,7 @@
                                        // siltenlty ignored
     assertEquals(0, doc.getFields().size());
   }
-  
+
   public void testConstructorExceptions() {
     FieldType ft = new FieldType();
     ft.setStored(true);
@@ -147,6 +148,34 @@
       // expected exception
     }
   }
+
+  public void testClearDocument() {
+    Document doc = makeDocumentWithFields();
+    assertEquals(8, doc.getFields().size());
+    doc.clear();
+    assertEquals(0, doc.getFields().size());
+  }
+
+  public void testGetFieldsImmutable() {
+    Document doc = makeDocumentWithFields();
+    assertEquals(8, doc.getFields().size());
+    List<Field> fields = doc.getFields();
+    try {
+      fields.add( new StringField("name", "value", Field.Store.NO) );
+      fail("Document.getFields() should return immutable List");
+    }
+    catch (UnsupportedOperationException e) {
+      // OK
+    }
+
+    try {
+      fields.clear();
+      fail("Document.getFields() should return immutable List");
+    }
+    catch (UnsupportedOperationException e) {
+      // OK
+    }
+  }
   
   /**
    * Tests {@link Document#getValues(String)} method for a brand new Document
Index: lucene/core/src/test/org/apache/lucene/index/TestIndexWriterExceptions.java
===================================================================
--- lucene/core/src/test/org/apache/lucene/index/TestIndexWriterExceptions.java	(revision 1371227)
+++ lucene/core/src/test/org/apache/lucene/index/TestIndexWriterExceptions.java	(working copy)
@@ -1556,50 +1556,66 @@
     try {
       doc = new Document();
       // try to boost with norms omitted
-      List<IndexableField> list = new ArrayList<IndexableField>();
-      list.add(new IndexableField() {
-
+      IndexDocument docList = new IndexDocument() {
+        
+        List<IndexableField> list = new ArrayList<IndexableField>();
+        List<StorableField> storedList = new ArrayList<StorableField>();
+        
         @Override
-        public String name() {
-          return "foo";
-        }
+        public Iterable<? extends IndexableField> indexableFields() {
+          if (list.size() == 0) {
+            list.add(new IndexableField() {
+              @Override
+              public String name() {
+                return "foo";
+              }
 
-        @Override
-        public IndexableFieldType fieldType() {
-          return StringField.TYPE_NOT_STORED;
-        }
+              @Override
+              public IndexableFieldType fieldType() {
+                return StringField.TYPE_NOT_STORED;
+              }
 
-        @Override
-        public float boost() {
-          return 5f;
-        }
+              @Override
+              public float boost() {
+                return 5f;
+              }
 
-        @Override
-        public BytesRef binaryValue() {
-          return null;
-        }
+              @Override
+              public BytesRef binaryValue() {
+                return null;
+              }
 
-        @Override
-        public String stringValue() {
-          return "baz";
-        }
+              @Override
+              public String stringValue() {
+                return "baz";
+              }
 
-        @Override
-        public Reader readerValue() {
-          return null;
-        }
+              @Override
+              public Reader readerValue() {
+                return null;
+              }
 
-        @Override
-        public Number numericValue() {
-          return null;
+              @Override
+              public Number numericValue() {
+                return null;
+              }
+
+              @Override
+              public TokenStream tokenStream(Analyzer analyzer) throws IOException {
+                return null;
+              }
+            });
+          }
+          return list;
         }
 
         @Override
-        public TokenStream tokenStream(Analyzer analyzer) throws IOException {
-          return null;
+        public Iterable<? extends StorableField> storableFields() {
+          return storedList;
         }
-      });
-      iw.addDocument(list);
+        
+      };
+      iw.addDocument(docList);
       fail("didn't get any exception, boost silently discarded");
     } catch (UnsupportedOperationException expected) {
       // expected
Index: lucene/grouping/src/test/org/apache/lucene/search/grouping/TestGrouping.java
===================================================================
--- lucene/grouping/src/test/org/apache/lucene/search/grouping/TestGrouping.java	(revision 1371227)
+++ lucene/grouping/src/test/org/apache/lucene/search/grouping/TestGrouping.java	(working copy)
@@ -594,7 +594,7 @@
         Document doc = new Document();
         docs.add(doc);
         if (groupValue.group != null) {
-          doc.add(newStringField("group", groupValue.group.utf8ToString(), Field.Store.NO));
+          doc.add(newStringField("group", groupValue.group.utf8ToString(), Field.Store.YES));
         }
         doc.add(newStringField("sort1", groupValue.sort1.utf8ToString(), Field.Store.NO));
         doc.add(newStringField("sort2", groupValue.sort2.utf8ToString(), Field.Store.NO));
Index: solr/core/src/java/org/apache/solr/handler/component/RealTimeGetComponent.java
===================================================================
--- solr/core/src/java/org/apache/solr/handler/component/RealTimeGetComponent.java	(revision 1371227)
+++ solr/core/src/java/org/apache/solr/handler/component/RealTimeGetComponent.java	(working copy)
@@ -298,7 +298,6 @@
   private static SolrDocument toSolrDoc(SolrInputDocument sdoc, IndexSchema schema) {
     // TODO: do something more performant than this double conversion
     Document doc = DocumentBuilder.toDocument(sdoc, schema);
-    List<IndexableField> fields = doc.getFields();
 
     // copy the stored fields only
     StoredDocument out = new StoredDocument();