@param cause the cause (can be retried by the {@link #getCause()} method).
   *          (A <tt>null</tt> value is permitted, and indicates that the cause
   *          is nonexistent or unknown.)
@param cause the cause (can be retried by the {@link #getCause()} method).
   *          (A <tt>null</tt> value is permitted, and indicates that the cause
   *          is nonexistent or unknown.) | RpcServerException.java