code: public void setEnvelope(Envelope env) {
  		if (!m_description.equals(env.getDescription()))
  			throw new IllegalArgumentException();
  
  		// m_envelope = (Envelope) env.clone();
  		m_envelope = (Envelope) env.createInstance();
  		env.copyTo(m_envelope);
  		_setDirtyFlag(DirtyFlags.DirtyIntervals, false);
  	}
docs: Sets the envelope of the Geometry. The Envelope description must match
  that of the Geometry.