docs: protected List<Principal> createRolePrincipals(UnixUser username) {
          ArrayList<Principal> principals = new ArrayList<Principal>();
          if (null != supplementalRoles) {
              for (String supplementalRole : supplementalRoles) {
                  Principal rolePrincipal = createRolePrincipal(supplementalRole);
                  if (null != rolePrincipal) {
                      principals.add(rolePrincipal);
                  }
              }
          }
          if (useUnixGroups) {
              for (String s : username.getGroups()) {
                  Principal rolePrincipal = createRolePrincipal(s);
                  if (null != rolePrincipal) {
                      principals.add(rolePrincipal);
                  }
              }
          }
          return principals;
      }