Latest version of org.specs2:specs2-matcher-extra_2.12.0-M5
https://javadoc.io/doc/org.specs2/specs2-matcher-extra_2.12.0-M5
Current version 3.8.4-20160825165200-b474dc3
https://javadoc.io/doc/org.specs2/specs2-matcher-extra_2.12.0-M5/3.8.4-20160825165200-b474dc3
package-list path (used for javadoc generation -link option)
https://javadoc.io/doc/org.specs2/specs2-matcher-extra_2.12.0-M5/3.8.4-20160825165200-b474dc3/package-list