code: private void writeMembershipType(MembershipType membershipType, Node mtNode) throws Exception
     {
        if (!mtNode.isNodeType("exo:datetime")) {
           mtNode.addMixin("exo:datetime");
        }
        mtNode.setProperty(MembershipTypeProperties.JOS_DESCRIPTION, membershipType.getDescription());
     }
docs: Writes membership type properties to the node.
  
  @param membershipType
  the membership type to store
  @param mtNode
  the node where membership type properties will be stored