Rename default branch to main

Closes gh-299

CONTRIBUTING.md

@@ -31,7 +31,7 @@ None of these is essential for a pull request, but they will all help
   than cosmetic changes).
 - Add some Javadocs
 - Add unit tests that covers and new or modified functionality
-- Whenever possible, please rebase your branch against the current master (or other
+- Whenever possible, please rebase your branch against the current main (or other
   target branch in the main project).
 - When writing a commit message please follow [these conventions][3]. Also, if you are
   fixing an existing issue please add `Fixes gh-nnn` at the end of the commit message

ci/parameters.yml

@@ -2,7 +2,7 @@ github-repo: "https://github.com/spring-gradle-plugins/dependency-management-plu
 github-repo-name: "spring-gradle-plugins/dependency-management-plugin"
 docker-hub-organization: "springci"
 artifactory-server: "https://repo.spring.io"
-branch: "master"
+branch: "main"
 build-name: "dependency-management-plugin"
 bintray-subject: "spring"
 bintray-repo: "jars"