I tried to export a metamodel into jmm and import it in a new project.
The exported metamodel does not contain any class definition.
Here the content of the jmm file

{
"format_version": "1.0",
"metadata": {
"name": "EduKG Core",
"version": "2.5",
"author": "Riccardo",
"description": "A new Project. Created by rik1599 @3/16/2026, 3:56:10 PM",
"exported_at": "2026-03-17T13:18:18.367Z",
"source_project": "Pointer1773672970291_USER_164",
"jjodel_version": "2.0"
},
"metamodel": {
"className": "DModel",
"id": "Pointer1773672995765_USER_186",
"pointedBy": [
{
"source": "models"
},
{
"source": "idlookup.Pointer1773672995767_USER_187.father"
},
{
"source": "idlookup.Pointer1773672995765_USER_186_graph1.model"
},
{
"source": "m2models"
},
{
"source": "models"
},
{
"source": "idlookup.Pointer1773672970291_USER_164.metamodels"
},
{
"source": "idlookup.Pointer1773672995765_USER_186_graph0.model"
},
{
"source": "idlookup.Pointer1773739458448_USER_172891.dependencies"
},
{
"source": "idlookup.Pointer1773745492302_USER_62696.dependencies"
},
{
"source": "idlookup.Pointer1773738426547_USER_14929.dependencies"
},
{
"source": "idlookup.Pointer1773745898783_USER_147762.instanceof"
},
{
"source": "idlookup.Pointer1773748786439_USER_34140.instanceof"
},
{
"source": "idlookup.Pointer1773752318146_USER_620111.dependencies"
}
],
"_state": {},
"name": "EduKG Core",
"parent": [],
"annotations": [],
"packages": [
"Pointer1773672995767_USER_187"
],
"isMetamodel": true,
"objects": [],
"models": [],
"instanceof": null,
"instances": [
"Pointer1773745898783_USER_147762"
],
"dependencies": [],
"clonedCounter": 7
}
}