@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		EdgeMarker other = (EdgeMarker) obj;
		if (_source == null) {
			if (other._source != null)
				return false;
		} else if (!_source.equals(other._source))
			return false;
		if (_target == null) {
			if (other._target != null)
				return false;
		} else if (!_target.equals(other._target))
			return false;
		return true;
	}