code: public AccessTokenInfo validate(String accessToken, String[] requiredScopes) throws WebApplicationException
      {
          return validate(accessToken, requiredScopes, null, null);
      }
docs: Validate an access token. This method is an alias of {@link
  #validate(String, String[], String)
  validate}<code>(accessToken, requiredScopes, null)</code>.
  
  </p>
  When the given access token is not valid, this method throws a
  {@link WebApplicationException}. The response contained in the
  exception complies with the requirements described in <a href=
  "http://tools.ietf.org/html/rfc6750">RFC 6750</a> (The OAuth
  2.0 Authorization Framework: Bearer Token Usage).
  </p>
  
  @param accessToken
  An access token to validate.
  
  @param requiredScopes
  Scopes that must be associated with the access token.
  {@code null} is okay.
  
  @return
  Information about the access token.
  
  @throws WebApplicationException
  The access token is invalid. To be concrete, one or more of
  the following conditions meet.
  <ol>
  <li>The access token does not exist.
  <li>The access token has expired.
  <li>The access token does not cover the required scopes.
  </ol>