code: public byte[] getObjectType() {
          return this.objectType == null || this.objectType.length == 0
                  ? null
                  : Arrays.copyOf(this.objectType, this.objectType.length);
      }
docs: A GUID (16 bytes) that identifies a property set, property, extended right, or type of child object. The purpose
  of this GUID depends on the user rights specified in the Mask field. This field is valid only if the ACE
  _OBJECT_TYPE_PRESENT bit is set in the Flags field. Otherwise, the ObjectType field is ignored. For information
  on access rights and for a mapping of the control access rights to the corresponding GUID value that identifies
  each right, see [MS-ADTS] sections 5.1.3.2 and 5.1.3.2.1.
  
  ACCESS_MASK bits are not mutually exclusive. Therefore, the ObjectType field can be set in an ACE with any
  ACCESS_MASK. If the AccessCheck algorithm calls this ACE and does not find an appropriate GUID, then that ACE
  will be ignored. For more information on access checks and object access, see [MS-ADTS] section 5.1.3.3.3.
  
  @return ObjectType; null if not available.