The installation of the Subversive SVN Connectors currently fails with Eclipse Oxygen.
eclipse.log
!ENTRY org.eclipse.team.svn.core.svnnature 4 0 2017-07-03 10:55:36.977
!MESSAGE SVN: 'SVN Decorator' operation finished with error
!SUBENTRY 1 org.eclipse.team.svn.core.svnnature 4 0 2017-07-03 10:55:36.977
!MESSAGE SVN: 'SVN Decorator' operation finished with error: Selected SVN connector library is not available or cannot be loaded.
If you selected native JavaHL connector, please check if binaries are available or install and select pure Java Subversion connector from the plug-in connectors update site.
If connectors already installed then you can change the selected one at: Window->Preferences->Team->SVN->SVN Connector.
!STACK 0
org.eclipse.team.svn.core.operation.UnreportableException: Selected SVN connector library is not available or cannot be loaded.
If you selected native JavaHL connector, please check if binaries are available or install and select pure Java Subversion connector from the plug-in connectors update site.
If connectors already installed then you can change the selected one at: Window->Preferences->Team->SVN->SVN Connector.
See also the bug report in the eclipse bugzilla https://bugs.eclipse.org/bugs/show_bug.cgi?id=518033
You can manually install the Subversive SVN Connectors by adding the update site https://community.polarion.com/projects/subversive/download/eclipse/6.0/update-site/ (check latest stable update site here: https://polarion.plm.automation.siemens.com/products/svn/subversive/download) and installing the necessary packages, e.g. for native 1.9.x in Eclipse x86: