fixes #2268 (#2281)

apollo-client/src/main/java/com/ctrip/framework/apollo/spring/property/SpringValueRegistry.java

@@ -11,6 +11,8 @@ import java.util.Map.Entry;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
+
+import com.google.common.collect.Multimaps;
 import org.springframework.beans.factory.BeanFactory;
 
 public class SpringValueRegistry {
@@ -23,7 +25,7 @@ public class SpringValueRegistry {
     if (!registry.containsKey(beanFactory)) {
       synchronized (LOCK) {
         if (!registry.containsKey(beanFactory)) {
-          registry.put(beanFactory, LinkedListMultimap.<String, SpringValue>create());
+          registry.put(beanFactory, Multimaps.synchronizedListMultimap(LinkedListMultimap.<String, SpringValue>create()));
         }
       }
     }