asciidoctor-epub3: `cannot load such file -- kindlegen` on Linux

Following on https://github.com/asciidoctor/asciidoctor-maven-examples/issues/77. The issue still appears with alpha.11 building with maven and the gem, even on Linux. For the gem build I am running asciidoctor -b epub3 -r asciidoctor-epub3 -a ebook-format=kf8 spine.adoc.

As another sad note, the workarround to call the maven build setting the envar KINDLEGEN=$(which kindlegen), does not work with alpha.11, it did with alpha.10.

Ruby environemnt Already installe Ruby 2.6.4 (ruby 2.6.4p104 (2019-08-28 revision 67798) [x86_64-linux]) Gem installed

• NOKOGIRI_USE_SYSTEM_LIBRARIES=1 gem install asciidoctor-epub3 --pre

Maven environement Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f) Maven home: —/.sdkman/candidates/maven/current Java version: 11.0.6, vendor: AdoptOpenJDK, runtime: —/.sdkman/candidates/java/11.0.6.hs-adpt Default locale: en_US, platform encoding: UTF-8 OS name: “linux”, version: “5.4.13-3-manjaro”, arch: “amd64”, family: “unix”