added ability to set field exclusion policies for json serialization

core/src/main/java/org/jclouds/json/config/GsonModule.java

@@ -59,6 +59,8 @@ import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
 import com.google.common.primitives.Bytes;
+import com.google.gson.ExclusionStrategy;
+import com.google.gson.FieldAttributes;
 import com.google.gson.FieldNamingStrategy;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
@@ -88,12 +90,14 @@ public class GsonModule extends AbstractModule {
          ByteArrayAdapter byteArrayAdapter, PropertiesAdapter propertiesAdapter, JsonAdapterBindings bindings,
          OptionalTypeAdapterFactory optional, SetTypeAdapterFactory set, MapTypeAdapterFactory map,
          MultimapTypeAdapterFactory multimap, IterableTypeAdapterFactory iterable,
-         CollectionTypeAdapterFactory collection, FluentIterableTypeAdapterFactory fluentIterable) throws Exception {
+         CollectionTypeAdapterFactory collection, FluentIterableTypeAdapterFactory fluentIterable,
+         DefaultExclusionStrategy exclusionStrategy) {
 
       FieldNamingStrategy serializationPolicy = new AnnotationOrNameFieldNamingStrategy(ImmutableSet.of(
             new ExtractSerializedName(), new ExtractNamed()));
 
-      GsonBuilder builder = new GsonBuilder().setFieldNamingStrategy(serializationPolicy);
+      GsonBuilder builder = new GsonBuilder().setFieldNamingStrategy(serializationPolicy)
+                                             .setExclusionStrategies(exclusionStrategy);
 
       // simple (type adapters)
       builder.registerTypeAdapter(Properties.class, propertiesAdapter.nullSafe());
@@ -130,6 +134,20 @@ public class GsonModule extends AbstractModule {
       return builder.create();
    }
 
+   @ImplementedBy(NoExclusions.class)
+   public static interface DefaultExclusionStrategy extends ExclusionStrategy {
+   }
+
+   public static class NoExclusions implements DefaultExclusionStrategy {
+      public boolean shouldSkipField(FieldAttributes f) {
+         return false;
+      }
+
+      public boolean shouldSkipClass(Class<?> clazz) {
+         return false;
+      }
+   }
+   
    @ImplementedBy(CDateAdapter.class)
    public abstract static class DateAdapter extends TypeAdapter<Date> {
 

core/src/test/java/org/jclouds/json/JsonTest.java

@@ -24,11 +24,14 @@ import java.util.Map;
 import java.util.Properties;
 
 import org.jclouds.json.config.GsonModule;
+import org.jclouds.json.config.GsonModule.DefaultExclusionStrategy;
 import org.testng.annotations.Test;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
+import com.google.gson.FieldAttributes;
+import com.google.inject.AbstractModule;
 import com.google.inject.Guice;
 import com.google.inject.TypeLiteral;
 
@@ -82,6 +85,26 @@ public class JsonTest {
       assertEquals(json.toJson(obj2), json.toJson(obj));
    }
    
+   static class ExcludeStringValue implements DefaultExclusionStrategy {
+      public boolean shouldSkipClass(Class<?> clazz) {
+        return false;
+      }
+
+      public boolean shouldSkipField(FieldAttributes f) {
+        return f.getName().equals("stringValue");
+      }
+   }
+
+   public void testExcluder() {
+      Json excluder = Guice.createInjector(new GsonModule(), new AbstractModule() {
+         protected void configure() {
+            bind(DefaultExclusionStrategy.class).to(ExcludeStringValue.class);
+         }
+      }).getInstance(Json.class);
+      ObjectNoDefaultConstructor obj = new ObjectNoDefaultConstructor("foo", 1);
+      assertEquals(excluder.toJson(obj), "{\"intValue\":1}");
+   }
+
    private static class EnumInside {
       private static enum Test {
          FOO, BAR;