code: public String getExplanation() {
          final StringBuilder sb = new StringBuilder();
          if (getMessage() != null) {
              sb.append(getMessage());
          }
          if (getCause() != null) {
              sb.append(getCause().getClass().getSimpleName());
          }
  
          return sb.toString();
      }
docs: Return the explanation of the exception.
  
  @return the exception explanation