code: public void addVars(Map<String, String> env) {
          if (tagUrl != null) {
              env.put("RELEASE_SCM_TAG", tagUrl);
              env.put(RT_RELEASE_STAGING + "SCM_TAG", tagUrl);
          }
          if (releaseBranch != null) {
              env.put("RELEASE_SCM_BRANCH", releaseBranch);
              env.put(RT_RELEASE_STAGING + "SCM_BRANCH", releaseBranch);
          }
          if (releaseVersion != null) {
              env.put(RT_RELEASE_STAGING + "VERSION", releaseVersion);
          }
          if (nextVersion != null) {
              env.put(RT_RELEASE_STAGING + "NEXT_VERSION", nextVersion);
          }
      }
docs: Add some of the release build properties to a map.