[Java] Upgrade to Gradle 6.8.3 and Mockito 3.8.0.

Author: mjpt777

build.gradle

@@ -47,7 +47,7 @@ def toolchainLauncher = javaToolchains.launcherFor {
 
 def checkstyleVersion = '8.39'
 def hamcrestVersion = '2.2'
-def mockitoVersion = '3.7.7'
+def mockitoVersion = '3.8.0'
 def junitVersion = '5.7.1'
 def jmhVersion = '1.27'
 def agronaVersion = '1.9.0'
@@ -723,6 +723,6 @@ task testReport(type: TestReport) {
 }
 
 wrapper {
- gradleVersion = '6.8.2'
+ gradleVersion = '6.8.3'
  distributionType = 'ALL'
 }

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.8.2-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.8.3-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists