Upgrade dependencies (#55)

* Upgrade Gradle version to 5.6.1

This commit also adjusts build.gradle files, so that they are compatible
with the new Gradle version.

Protobuf plugin now requires Java 8. This is reflected in README.md

I've checked the new configuration works by invoking Gradle tasks:
project tasks build check clean eclipse javadoc.

* Update the dependency versions of gRPC and Protobuf.

As those libraries provide a BOM, we can put version dependency on BOM
file as well.

Author: tomboc

build.gradle

@@ -76,6 +76,18 @@ subprojects {
     sourceCompatibility = project.sourceCompatibility
     targetCompatibility = project.targetCompatibility
   }
+
+  ext {
+    libraries = [
+      grpcBom: "io.grpc:grpc-bom:${grpcVersion}",
+      grpcStub: "io.grpc:grpc-stub",
+      grpcProtobuf: "io.grpc:grpc-protobuf",
+
+      protobufJavaBom: "com.google.protobuf:protobuf-bom:${protobufJavaVersion}",
+      protobufJava: "com.google.protobuf:protobuf-java",
+      protobufJavaUtil: "com.google.protobuf:protobuf-java-util",
+    ]
+  }
 }
 
 def configureMaven(project, projectName, projectDescription) {

endpoints-management-protos/build.gradle

@@ -12,30 +12,33 @@ apply plugin: 'com.google.protobuf'
 
 description = 'GRPC library for the servicecontrol-v1 service'
 // TODO: use a flag to determine whether to produce a release or a snapshot
-sourceCompatibility = 1.6
-targetCompatibility = 1.6
+sourceCompatibility = 1.8
+targetCompatibility = 1.8
 
 repositories {
   mavenCentral()
   mavenLocal()
 }
 
 dependencies {
-  compile "com.google.protobuf:protobuf-java:3.0.0"
-  compile "io.grpc:grpc-protobuf:1.14.0"
-  compile "io.grpc:grpc-stub:1.14.0"
+  compile platform(libraries.protobufJavaBom),
+          libraries.protobufJava
+
+  compile platform(libraries.grpcBom),
+          libraries.grpcStub,
+          libraries.grpcProtobuf
 }
 
 protobuf {
   protoc {
     // The version of protoc must match protobuf-java. If you don't depend on
     // protobuf-java directly, you will be transitively depending on the
     // protobuf-java version that grpc depends on.
-    artifact = "com.google.protobuf:protoc:3.0.0-beta-4"
+    artifact = "com.google.protobuf:protoc:${protobufJavaVersion}"
   }
   plugins {
     grpc {
-      artifact = 'io.grpc:protoc-gen-grpc-java:0.15.0'
+      artifact = "io.grpc:protoc-gen-grpc-java:${grpcVersion}"
     }
   }
   generateProtoTasks {

endpoints-service-config/build.gradle

@@ -23,12 +23,13 @@ archivesBaseName = 'endpoints-management-config'
 
 dependencies {
   compile(project(":endpoints-management-protos"))
-  compile "com.google.protobuf:protobuf-java:3.0.0"
+  compile platform(libraries.protobufJavaBom)
+  compile "com.google.protobuf:protobuf-java"
   compile "com.google.apis:google-api-services-servicemanagement:$servicemanagementVersion"
   compileOnly "com.google.appengine:appengine-api-1.0-sdk:$appengineSdkVersion"
   compile "com.google.guava:guava:$guavaVersion"
   compile "com.google.http-client:google-http-client:$httpClientVersion"
-  compile "com.google.protobuf:protobuf-java-util:$protobufUtilVersion"
+  compile "com.google.protobuf:protobuf-java-util"
 
   testCompile "org.mockito:mockito-core:$mockitoVersion"
   testCompile "junit:junit:$junitVersion"

gradle.properties

@@ -25,6 +25,7 @@ commonsLang3Version = 3.4
 googleApiClientProtobufVersion = 1.22.0
 googleApiClientAppEngineVersion = 1.22.0
 googleapisCommonProtosVersion = 0.0.3
+grpcVersion = 1.22.1
 grpcGoogleApiVersion = 0.7.0-SNAPSHOT
 guavaVersion = 19.0
 httpClientVersion = 1.22.0
@@ -33,7 +34,7 @@ jerseyVersion = 2.23.1
 jettyVersion = 9.3.0.M0
 jose4jVersion = 0.6.4
 jsr305Version = 2.0.1
-protobufUtilVersion = 3.0.0-beta-4
+protobufJavaVersion = 3.9.1
 servicemanagementVersion = v1-rev14-1.22.0
 servletApiVersion = 2.5
 truthVersion = 0.27