code: public final void setErrorMessage(@NonNull final CharSequence errorMessage) {
          Condition.INSTANCE.ensureNotNull(errorMessage, "The error message may not be null");
          Condition.INSTANCE.ensureNotEmpty(errorMessage, "The error message may not be empty");
          this.errorMessage = errorMessage;
      }
docs: Sets the error message, which should be shown, if the validation fails.
  
  @param errorMessage
  The error message, which should be set, as an instance of the type {@link
  CharSequence}. The error message may not be null