code: public static ConcurrentRuntimeException extractCauseUnchecked(
              final ExecutionException ex) {
          if (ex == null || ex.getCause() == null) {
              return null;
          }
  
          throwCause(ex);
          return new ConcurrentRuntimeException(ex.getMessage(), ex.getCause());
      }
docs: Inspects the cause of the specified {@code ExecutionException} and
  creates a {@code ConcurrentRuntimeException} with the checked cause if
  necessary. This method works exactly like
  {@link #extractCause(ExecutionException)}. The only difference is that
  the cause of the specified {@code ExecutionException} is extracted as a
  runtime exception. This is an alternative for client code that does not
  want to deal with checked exceptions.
  
  @param ex the exception to be processed
  @return a {@code ConcurrentRuntimeException} with the checked cause