fix NPE in ServiceTestUtil.java (#804)

diff --git a/dubbo-admin-server/src/main/java/org/apache/dubbo/admin/common/util/ServiceTestUtil.java b/dubbo-admin-server/src/main/java/org/apache/dubbo/admin/common/util/ServiceTestUtil.java
index fa568ff..e1dd54b 100644
--- a/dubbo-admin-server/src/main/java/org/apache/dubbo/admin/common/util/ServiceTestUtil.java
+++ b/dubbo-admin-server/src/main/java/org/apache/dubbo/admin/common/util/ServiceTestUtil.java
@@ -86,7 +86,7 @@
 
     private static TypeDefinition findTypeDefinition(ServiceDefinition serviceDefinition, String type) {
         return serviceDefinition.getTypes().stream()
-                .filter(t -> t.getType().equals(type))
+                .filter(t -> type.equals(t.getType()))
                 .findFirst().orElse(new TypeDefinition(type));
     }