[Java] Upgrade to javadoc-links 4.0.0 and Gradle Build Scan 2.4.1.

Author: mjpt777

build.gradle

@@ -21,8 +21,8 @@ buildscript {
 
 plugins {
  id 'java'
- id 'com.gradle.build-scan' version '2.3'
- id "io.freefair.javadoc-links" version "3.8.4" apply false
+ id 'com.gradle.build-scan' version '2.4.1'
+ id 'io.freefair.javadoc-links' version '4.0.0' apply false
  id 'com.github.johnrengelman.shadow' version '5.1.0' apply false
 }