diff --git a/oap-server/server-query-plugin/query-graphql-plugin/src/main/java/org/apache/skywalking/oap/query/graphql/GraphQLQueryHandler.java b/oap-server/server-query-plugin/query-graphql-plugin/src/main/java/org/apache/skywalking/oap/query/graphql/GraphQLQueryHandler.java
index ae805e42a91da01eb2d0f037a6b40c82600bec89..ad4dcf6d02bc887551341ae4aa4d55d08b1dafb1 100644
--- a/oap-server/server-query-plugin/query-graphql-plugin/src/main/java/org/apache/skywalking/oap/query/graphql/GraphQLQueryHandler.java
+++ b/oap-server/server-query-plugin/query-graphql-plugin/src/main/java/org/apache/skywalking/oap/query/graphql/GraphQLQueryHandler.java
@@ -30,6 +30,7 @@ import graphql.GraphQLError;
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.lang.reflect.Type;
 import java.util.List;
 import java.util.Map;
 import javax.servlet.http.HttpServletRequest;
@@ -51,6 +52,8 @@ public class GraphQLQueryHandler extends JettyJsonHandler {
     private static final String MESSAGE = "message";
 
     private final Gson gson = new Gson();
+    private final Type mapOfStringObjectType = new TypeToken<Map<String, Object>>() {
+    }.getType();
 
     private final String path;
 
@@ -75,8 +78,7 @@ public class GraphQLQueryHandler extends JettyJsonHandler {
 
         JsonObject requestJson = gson.fromJson(request.toString(), JsonObject.class);
 
-        return execute(requestJson.get(QUERY).getAsString(), gson.fromJson(requestJson.get(VARIABLES), new TypeToken<Map<String, Object>>() {
-        }.getType()));
+        return execute(requestJson.get(QUERY).getAsString(), gson.fromJson(requestJson.get(VARIABLES), mapOfStringObjectType));
     }
 
     private JsonObject execute(String request, Map<String, Object> variables) {
diff --git a/pom.xml b/pom.xml
index 8682040478753d262d66538ca5cbe10971c4c130..1527fec9a026573a89582706bcc1daef5b16ed4b 100644
--- a/pom.xml
+++ b/pom.xml
@@ -17,7 +17,8 @@
   ~
   -->
 
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
     <groupId>org.apache.skywalking</groupId>
@@ -82,7 +83,6 @@
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <compiler.version>1.8</compiler.version>
-        <scala.compiler.version>2.11.7</scala.compiler.version>
         <powermock.version>1.6.4</powermock.version>
         <checkstyle.version>6.18</checkstyle.version>
         <junit.version>4.12</junit.version>
@@ -114,13 +114,11 @@
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.mockito</groupId>
             <artifactId>mockito-all</artifactId>
-            <version>${mockito-all.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
@@ -140,13 +138,13 @@
             <dependency>
                 <groupId>junit</groupId>
                 <artifactId>junit</artifactId>
-                <version>4.12</version>
+                <version>${junit.version}</version>
                 <scope>test</scope>
             </dependency>
             <dependency>
                 <groupId>org.mockito</groupId>
                 <artifactId>mockito-all</artifactId>
-                <version>1.10.19</version>
+                <version>${mockito-all.version}</version>
                 <scope>test</scope>
             </dependency>
             <dependency>