https://wiki.jenkins-ci.org/display/JENKINS/Config+File+Provider+Plugin shows the use case, for the Maven case, the settings.xml file containing passwords is generated for the build by plucking the appropriate password from the credentials plugin.

For SBT, we want to generate the credentials properties file as outlined in http://stackoverflow.com/questions/4348805/how-to-access-a-secured-nexus-with-sbt.