code: @Override
  	protected boolean semanticallyEquivalent(BioPAXElement element)
  	{
  		if (!(element instanceof PhysicalEntity))
  			return false;
  
  		PhysicalEntity that = (PhysicalEntity) element;
  		return hasEquivalentCellularLocation(that)
  		       && hasEquivalentFeatures(that)
  		       && SetEquivalenceChecker
  				.isEquivalent(getMemberPhysicalEntity(), that.getMemberPhysicalEntity())
  		       &&
  		       super.semanticallyEquivalent(element); // StackOverflow BUG fixed: was isEquivalent !
  	}
docs: --------------------- Interface BioPAXElement ---------------------