switching from http://maven.research-infrastructures.eu to the updated maven repository https://maven.d4science.org
bumped apache.solr.version to 7.5.0
added property postgres.jdbc.version
updated guava version to 23.3-jre
fixed repo id
cleanup
sorte out issue with the javadoc breaking the release process
introducing <maven.javadoc.failOnError>false</maven.javadoc.failOnError> did not work, updated maven-javadoc-plugin to version 2.10.1
introduced <maven.javadoc.failOnError>false</maven.javadoc.failOnError> to avoid javadoc plugin to break the release process
changed repository visibility
preparing release
mimic mvn release procedure
fixed dnet releases url
codebase used to migrate to java8 the production system