public static StandardMapObjectInspector getStandardMapObjectInspector(
      ObjectInspector mapKeyObjectInspector,
      ObjectInspector mapValueObjectInspector) {
    ArrayList<ObjectInspector> signature = new ArrayList<ObjectInspector>(2);
    signature.add(mapKeyObjectInspector);
    signature.add(mapValueObjectInspector);
    StandardMapObjectInspector result = cachedStandardMapObjectInspector.asMap()
        .get(signature);
    if (result == null) {
      result = new StandardMapObjectInspector(mapKeyObjectInspector,
          mapValueObjectInspector);
      StandardMapObjectInspector prev =
        cachedStandardMapObjectInspector.asMap().putIfAbsent(signature, result);
      if (prev != null) {
        result = prev;
      }
    }
    return result;
  }
Verify that we don't have an unexpected type of object inspector.
@param option The option to verify
@param oi The ObjectInspector to verify
@param checkOption We're only interested in this option type
@param classes ObjectInspector should not be of these types
serde/src/java/org/apache/hadoop/hive/serde2/objectinspector/ObjectInspectorFactory.java