Updated gradle version to gradle 6

build.gradle

@@ -17,6 +17,7 @@ plugins {
     id 'me.champeau.gradle.jmh' version '0.4.5'
     id 'nebula.optional-base' version '3.2.0'
     id 'com.github.hierynomus.license' version '0.15.0'
+    id 'com.github.spotbugs' version "4.3.0"
 }
 
 allprojects {
@@ -44,19 +45,23 @@ allprojects {
 
 subprojects {
     apply plugin: 'com.jfrog.bintray'
-    apply plugin: 'findbugs'
+    apply plugin: 'com.github.spotbugs'
     apply plugin: 'jacoco'
     apply plugin: 'java'
     apply plugin: 'maven-publish'
     apply plugin: 'me.champeau.gradle.jmh'
     apply plugin: 'nebula.optional-base'
     apply plugin: 'com.github.hierynomus.license'
 
+
     sourceCompatibility = 1.8
     targetCompatibility = 1.8
 
     repositories {
         jcenter()
+        maven {
+            url 'https://plugins.gradle.org/m2/'
+        }
     }
 
     task sourcesJar(type: Jar, dependsOn: classes) {
@@ -74,15 +79,15 @@ subprojects {
         archives javadocJar
     }
 
-    tasks.withType(FindBugs) {
+    spotbugsMain {
         reports {
             xml.enabled = false
             html.enabled = true
         }
     }
 
-    findbugs {
-        findbugsJmh.enabled = false
+    spotbugs {
+        spotbugsJmh.enabled = false
     }
 
     test {
@@ -207,9 +212,9 @@ task jacocoRootReport(type: JacocoReport, group: 'Coverage reports') {
     description = 'Generates an aggregate report from all subprojects'
     dependsOn publishedProjects.test, jacocoMerge
 
-    additionalSourceDirs = files(publishedProjects.sourceSets.main.allSource.srcDirs)
-    sourceDirectories = files(publishedProjects.sourceSets.main.allSource.srcDirs)
-    classDirectories = files(publishedProjects.sourceSets.main.output)
+    getAdditionalSourceDirs().setFrom(files(publishedProjects.sourceSets.main.allSource.srcDirs))
+    getSourceDirectories().setFrom(files(publishedProjects.sourceSets.main.allSource.srcDirs))
+    getAdditionalClassDirs().setFrom(files(publishedProjects.sourceSets.main.output))
     executionData jacocoMerge.destinationFile
 
     reports {

core-httpclient-impl/src/test/java/com/optimizely/ab/OptimizelyHttpClientTest.java

@@ -1,6 +1,6 @@
 /**
  *
- *    Copyright 2019, Optimizely
+ *    Copyright 2019-2020, Optimizely
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -73,7 +73,7 @@ public void testProxySettings() throws IOException {
     @Test
     public void testExecute() throws IOException {
         HttpUriRequest httpUriRequest = RequestBuilder.get().build();
-        ResponseHandler<Boolean> responseHandler = response -> null;
+        ResponseHandler<Boolean> responseHandler = response -> false;
 
         CloseableHttpClient mockHttpClient = mock(CloseableHttpClient.class);
         when(mockHttpClient.execute(httpUriRequest, responseHandler)).thenReturn(true);

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.5.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.5-all.zip