[enhancement] Replace custom Callback with Java 8 Completable Future#67

damienbeaufils wants to merge 3 commits intoprismicio-community:masterprismicio-community/java-kit:masterfrom

damienbeaufils:replace-callback-with-java8-completable-futuredamienbeaufils/java-kit:replace-callback-with-java8-completable-futureCopy head branch name to clipboard