The documentation seems to indicate that the right maven repository to use is:
<repository> <id>osgeo</id> <name>Open Source Geospatial Foundation Repository</name> <url>http://download.osgeo.org/webdav/geotools/</url> </repository>
However, it seems that the latest version on this repository was last updated in 2014. https://mvnrepository.com/artifact/org.geotools.jdbc/gt-jdbc-postgis?repo=osgeo
On the other hand, the Boundless one seems to be carrying a much more updated version than the other repositories. This one was last updated in September 2018: https://mvnrepository.com/artifact/org.geotools.jdbc/gt-jdbc-postgis/20.0
However, the documentation states that the Boundless repository is for snapshots.
Which is the proper version to use?