Consolidates entrypoint where Hystrix is configured (#446)

hystrix/src/main/java/feign/hystrix/HystrixFeign.java

@@ -38,14 +38,7 @@ public final class HystrixFeign {
      * @see #target(Class, String, Object)
      */
     public <T> T target(Target<T> target, final T fallback) {
-      super.invocationHandlerFactory(new InvocationHandlerFactory() {
-        @Override
-        public InvocationHandler create(Target target, Map<Method, MethodHandler> dispatch) {
-          return new HystrixInvocationHandler(target, dispatch, fallback);
-        }
-      });
-      super.contract(new HystrixDelegatingContract(contract));
-      return super.build().newInstance(target);
+      return buildWithFallback(fallback).newInstance(target);
     }
 
     /**
@@ -100,7 +93,17 @@ public final class HystrixFeign {
 
     @Override
     public Feign build() {
-      super.invocationHandlerFactory(new HystrixInvocationHandler.Factory());
+      return buildWithFallback(null);
+    }
+
+    /** Configures components needed for hystrix integration. */
+    Feign buildWithFallback(final Object nullableFallback) {
+      super.invocationHandlerFactory(new InvocationHandlerFactory() {
+        @Override public InvocationHandler create(Target target,
+            Map<Method, MethodHandler> dispatch) {
+          return new HystrixInvocationHandler(target, dispatch, nullableFallback);
+        }
+      });
       super.contract(new HystrixDelegatingContract(contract));
       return super.build();
     }

hystrix/src/main/java/feign/hystrix/HystrixInvocationHandler.java

@@ -19,7 +19,6 @@ import com.netflix.hystrix.HystrixCommand;
 import com.netflix.hystrix.HystrixCommandGroupKey;
 import com.netflix.hystrix.HystrixCommandKey;
 
-import com.netflix.hystrix.HystrixCommandProperties;
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
@@ -27,7 +26,6 @@ import java.lang.reflect.Proxy;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
-import feign.InvocationHandlerFactory;
 import feign.InvocationHandlerFactory.MethodHandler;
 import feign.Target;
 import rx.Completable;
@@ -183,12 +181,4 @@ final class HystrixInvocationHandler implements InvocationHandler {
   public String toString() {
     return target.toString();
   }
-
-  static final class Factory implements InvocationHandlerFactory {
-
-    @Override
-    public InvocationHandler create(Target target, Map<Method, MethodHandler> dispatch) {
-      return new HystrixInvocationHandler(target, dispatch, null);
-    }
-  }
-}
+}