adding an option to page from ListResult

src/main/java/com/google/gcloud/ServiceOptions.java

@@ -283,7 +283,7 @@ public AuthCredentials authCredentials() {
   }
 
   public RetryParams retryParams() {
-    return retryParams;
+    return retryParams != null ? retryParams : RetryParams.noRetries();
   }
 
   public ServiceRpcFactory<R, O> serviceRpcFactory() {

src/main/java/com/google/gcloud/datastore/DatastoreServiceOptions.java

@@ -44,6 +44,7 @@ public class DatastoreServiceOptions extends ServiceOptions<DatastoreRpc, Datast
   private final String namespace;
   private final boolean force;
   private final boolean normalizeDataset;
+  private transient DatastoreRpc datastoreRpc;
 
   public static class Builder extends
       ServiceOptions.Builder<DatastoreRpc, DatastoreServiceOptions, Builder> {
@@ -178,10 +179,15 @@ public boolean equals(Object obj) {
   }
 
   DatastoreRpc datastoreRpc() {
+    if (datastoreRpc != null) {
+      return datastoreRpc;
+    }
     if (serviceRpcFactory() != null) {
-      return serviceRpcFactory().create(this);
+      datastoreRpc = serviceRpcFactory().create(this);
+    } else {
+      datastoreRpc = ServiceRpcProvider.datastore(this);
     }
-    return ServiceRpcProvider.datastore(this);
+    return datastoreRpc;
   }
 
   public static DatastoreServiceOptions defaultInstance() {

src/main/java/com/google/gcloud/storage/BatchRequest.java

@@ -96,15 +96,15 @@ public boolean equals(Object obj) {
         && Objects.equals(toGet, other.toGet);
   }
 
-  Map<Blob, Iterable<BlobSourceOption>> toDelete() {
+  public Map<Blob, Iterable<BlobSourceOption>> toDelete() {
     return toDelete;
   }
 
-  Map<Blob, Iterable<BlobTargetOption>> toUpdate() {
+  public Map<Blob, Iterable<BlobTargetOption>> toUpdate() {
     return toUpdate;
   }
 
-  Map<Blob, Iterable<BlobSourceOption>> toGet() {
+  public Map<Blob, Iterable<BlobSourceOption>> toGet() {
     return toGet;
   }
 

src/main/java/com/google/gcloud/storage/BatchResponse.java

@@ -43,12 +43,12 @@ public static class Result<T extends Serializable> implements Serializable {
     private final StorageServiceException exception;
 
 
-    Result(T value) {
+    public Result(T value) {
       this.value = value;
       this.exception = null;
     }
 
-    Result(StorageServiceException exception) {
+    public Result(StorageServiceException exception) {
       this.exception = exception;
       this.value = null;
     }
@@ -112,7 +112,7 @@ static <T extends Serializable> Result<T> empty() {
     }
   }
 
-  BatchResponse(List<Result<Boolean>> deleteResult, List<Result<Blob>> updateResult,
+  public BatchResponse(List<Result<Boolean>> deleteResult, List<Result<Blob>> updateResult,
       List<Result<Blob>> getResult) {
     this.deleteResult = ImmutableList.copyOf(deleteResult);
     this.updateResult = ImmutableList.copyOf(updateResult);

src/main/java/com/google/gcloud/storage/ListResult.java

@@ -31,16 +31,35 @@ public final class ListResult<T extends Serializable> implements Iterable<T>, Se
 
   private final String cursor;
   private final Iterable<T> results;
+  private final NextPageFetcher<T> pageFetcher;
 
-  ListResult(String cursor, Iterable<T> results) {
+  interface NextPageFetcher<T extends Serializable> extends Serializable {
+    ListResult<T> nextPage();
+  }
+
+  public ListResult(NextPageFetcher<T> pageFetcher, String cursor, Iterable<T> results) {
+    this.pageFetcher = pageFetcher;
     this.cursor = cursor;
     this.results = results;
   }
 
+  /**
+   * Returns the cursor for the nextPage or {@code null} if no more results.
+   */
   public String nextPageCursor() {
     return cursor;
   }
 
+  /**
+   * Returns the results of the nextPage or {@code null} if no more result.
+   */
+  public ListResult<T> nextPage() {
+    if (cursor == null || pageFetcher == null) {
+      return null;
+    }
+    return pageFetcher.nextPage();
+  }
+
   @Override
   public Iterator<T> iterator() {
     return results == null ? Collections.<T>emptyIterator() : results.iterator();