@kai @bastiaan_van_h i had multiple Java JDKs installed.
Removed all JRE/JDK, installed only 1.8.0_162 change windows path, JAVA_HOME. cleaned C:\Users\<UserName>\.m2 and C:\Users\<UserName>\.eclipse
Reinstalled eclipse with the smarthome repo and got it running after a mvn clean install.
There are multiple configuration points where the right path has to be set. The proccess described above makes sure, or did for me, that all path configurations are reseted and can be set during the fresh installation.
Hope this helps anyone with a similar problem.