code: @Nonnull
      public static String tokenFor(String credentialsId) {
          return secretFor(credentialsId).or(new Supplier<Secret>() {
              @Override
              public Secret get() {
                  return Secret.fromString(UNKNOWN_TOKEN);
              }
          }).getPlainText();
      }
docs: Extracts token from secret found by {@link #secretFor(String)}
  Returns {@link #UNKNOWN_TOKEN} if no any creds secret found with this id.
  
  @param credentialsId id to find creds
  
  @return token from creds or default non empty string