@Override
	public ArrayList<Diagnostic> identify(SchemaNode node) {
        ArrayList<Diagnostic> ret = new ArrayList<>();

        if (!node.isSchemaASTInstance(identifierStr.class)) return ret;
        if (node.getParent() == null || !node.getParent().getSchemaNode().isSchemaASTInstance(inheritsStruct.class)) return ret;

        if (!node.hasSymbol()) {
            ret.add(new SchemaDiagnostic.Builder()
                .setRange(node.getRange())
                .setMessage("Should be reference")
                .setSeverity(DiagnosticSeverity.Warning)
                .build());
        }

        context.addUnresolvedInheritanceNode(node);

        return ret;
	}
IdentifyStructInheritance identifies if a struct inherits from another struct and adds it to a list to resolve later
integration/schema-language-server/language-server/src/main/java/ai/vespa/schemals/schemadocument/parser/schema/IdentifyStructInheritance.java