@Override
  public String toString() {
    return "(" + (schema == null ? "" : ", schema = " + schema + ", ") + "message = " + message + ")";
  }
Encapsulates the basic response info returned by classes the implement the
<code>CommandProcessor</code> interface. Typically <code>errorMessage</code>
and <code>SQLState</code> will only be set if the <code>responseCode</code>
is not 0.  Note that often {@code responseCode} ends up the exit value of
command shell process so should keep it to &lt; 127.
ql/src/java/org/apache/hadoop/hive/ql/processors/CommandProcessorResponse.java