Version 1.8 does not work for GWT anymore

Version 1.8 does not work for GWT anymore, because the source artifact (on maven https://search.maven.org/remotecontent?filepath=com/google/re2j/re2j/1.8/re2j-1.8-sources.jar and via release download https://github.com/google/re2j/releases/download/re2j-1.8/re2j-1.8-sources.jar) does not contain the GWT super source folder anymore (with the emulated GWT version of Characters.java) , like in 1.7:
re2j-1.7-sources.jar\com\google\re2j\super\com\google\re2j\Characters.java

I assume this is somehow lost in the packaging process, because it's still (unchnaged) in the repository https://github.com/google/re2j/blob/master/java/com/google/re2j/super/com/google/re2j/Characters.java