@Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        final ObjectPropertyIdentifier other = (ObjectPropertyIdentifier) obj;
        if (objectType == null) {
            if (other.objectType != null)
                return false;
        }
        else if (!objectType.equals(other.objectType))
            return false;
        if (propertyIdentifier == null) {
            if (other.propertyIdentifier != null)
                return false;
        }
        else if (!propertyIdentifier.equals(other.propertyIdentifier))
            return false;
        return true;
    }