Update gRPC version to 1.41.0 (#318)

* update grpc version to 1.38.0

Signed-off-by: birdstorm <samuelwyf@hotmail.com>

pom.xml

@@ -62,7 +62,8 @@
         <protobuf.version>3.5.1</protobuf.version>
         <log4j.version>1.2.17</log4j.version>
         <slf4j.version>1.7.16</slf4j.version>
-        <grpc.version>1.24.0</grpc.version>
+        <grpc.version>1.38.0</grpc.version>
+        <gson.version>2.8.5</gson.version>
         <powermock.version>1.6.6</powermock.version>
         <jackson.version>2.10.0</jackson.version>
         <trove4j.version>3.0.1</trove4j.version>
@@ -137,6 +138,11 @@
             <version>${grpc.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+            <version>${gson.version}</version>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-annotations</artifactId>

src/main/java/org/tikv/common/util/ChannelFactory.java

@@ -51,7 +51,7 @@ public class ChannelFactory implements AutoCloseable {
           // So a coarse grain lock is ok here
           return ManagedChannelBuilder.forAddress(mappedAddr.getHost(), mappedAddr.getPort())
               .maxInboundMessageSize(maxFrameSize)
-              .usePlaintext(true)
+              .usePlaintext()
               .idleTimeout(60, TimeUnit.SECONDS)
               .build();
         });