default Principal authenticate(Properties props) throws AuthenticationFailedException {
    return authenticate(props, null);
  }
Verify the credentials provided in the properties for the client/peer as specified in member ID
and returns the principal associated with the client/peer.

@param props the credentials of the client/peer as a set of property key/values
@param member the {@link DistributedMember} object of the connecting client/peer member. NULL
       when invoked locally on the member initiating the authentication request.

@return the principal for the client/peer when authentication succeeded

@throws AuthenticationFailedException If the authentication of the client/peer fails.
geode-core/src/main/java/org/apache/geode/security/Authenticator.java