@Override
    protected Object processResponse(final @NotNull Message msg) throws Exception {
      return null;
    }
Sends the auth credentials to the server for a particular user. Used in multiple user mode of
authentication.

@param location The ServerLocation instance whose connection instance will be used to perform
       the operation.
@param pool The connection pool to use for this operation.
@return Object unique user-id.
geode-core/src/main/java/org/apache/geode/cache/client/internal/AuthenticateUserOp.java