fix referenceBean initialization issue (apache#2719)

dubbo-config/dubbo-config-api/src/main/java/com/alibaba/dubbo/config/ReferenceConfig.java

@@ -419,6 +419,8 @@ private T createProxy(Map<String, String> map) {
             c = true; // default true
         }
         if (c && !invoker.isAvailable()) {
+            // make it possible for consumer to retry later if provider is temporarily unavailable
+            initialized = false;
             throw new IllegalStateException("Failed to check the status of the service " + interfaceName + ". No provider available for the service " + (group == null ? "" : group + "/") + interfaceName + (version == null ? "" : ":" + version) + " from the url " + invoker.getUrl() + " to the consumer " + NetUtils.getLocalHost() + " use dubbo version " + Version.getVersion());
         }
         if (logger.isInfoEnabled()) {

dubbo-config/dubbo-config-api/src/test/java/com/alibaba/dubbo/config/ReferenceConfigTest.java

@@ -59,5 +59,45 @@ public void testInjvm() throws Exception {
             demoService.unexport();
         }
     }
-
-}
+    /**
+     * unit test for dubbo-1765
+     */
+    @Test
+    public void testReferenceRetry() {
+        ApplicationConfig application = new ApplicationConfig();
+        application.setName("test-reference-retry");
+        RegistryConfig registry = new RegistryConfig();
+        registry.setAddress("multicast://224.5.6.7:1234");
+        ProtocolConfig protocol = new ProtocolConfig();
+        protocol.setName("dubbo");
+        ReferenceConfig<DemoService> rc = new ReferenceConfig<DemoService>();
+        rc.setApplication(application);
+        rc.setRegistry(registry);
+        rc.setInterface(DemoService.class.getName());
+        boolean success = false;
+        DemoService demoService = null;
+        try {
+            demoService = rc.get();
+            success = true;
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        Assert.assertFalse(success);
+        Assert.assertNull(demoService);
+        ServiceConfig<DemoService> sc = new ServiceConfig<DemoService>();
+        sc.setInterface(DemoService.class);
+        sc.setRef(new DemoServiceImpl());
+        sc.setApplication(application);
+        sc.setRegistry(registry);
+        sc.setProtocol(protocol);
+        try {
+            sc.export();
+            demoService = rc.get();
+            success = true;
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        Assert.assertTrue(success);
+        Assert.assertNotNull(demoService);
+    }
+}