code: public void setAccessToken(final String accessToken, final Long expiresIn) {
      for (Authentication auth : authentications.values()) {
        if (auth instanceof OAuth) {
          ((OAuth) auth).setAccessToken(accessToken, expiresIn);
          return;
        }
      }
      OAuth oAuth = new OAuth(null, null, null) {
        @Override
        public void applyToParams(List<Pair> queryParams, Map<String, String> headerParams) {
          headerParams.put("Authorization", "Bearer " + accessToken);
        }
      };
      oAuth.setAccessToken(accessToken, expiresIn);
      addAuthorization("docusignAccessCode", oAuth);
      // throw new RuntimeException("No OAuth2 authentication configured!");
    }
docs: Helper method to preset the OAuth access token of the first OAuth found in the apiAuthorizations (there should be only one)
  @param accessToken OAuth access token
  @param expiresIn Validity period of the access token in seconds