code: public static <T> T checkNotEmpty(T reference,  Object errorMessage) {
          checkNotNull(reference, "Expected not null object, got '%s'", reference);
          checkNotEmpty(reference, String.valueOf(errorMessage), Arrays2.EMPTY_ARRAY);
          return reference;
      }
docs: Performs emptiness and nullness check.
  @see #checkNotEmpty(Object, String, Object...)