For future reference:
There is an error building LanguageTool with Maven and Java 11. With Java 8 the issue disappears.
I attach the stack trace given by Eclipse in the file languagetool-core/pom.xml
languagetool-error-maven-java11.zip (1.4 KB)
In the maven command line the error is:
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] /home/jaume/github/languagetool/languagetool-core/target/generated-sources/protobuf/grpc-java/org/languagetool/languagemodel/bert/grpc/BertLmGrpc.java:[20,18] cannot find symbol
symbol: class Generated
location: package javax.annotation