code: public void setObjectType(final byte[] objectType) {
          this.objectType = objectType == null || objectType.length == 0
                  ? null
                  : Arrays.copyOf(objectType, objectType.length);
      }
docs: Sets object type, a GUID (16 bytes) that identifies a property set, property, extended right, or type of child
  object.
  
  @param objectType ACE object type.