Bad Behaviour of IChangeSerializer regarding unassigned keyword

given the grammar

Model:
	"model" name=ID "{"
		(expressions+=Expression ';'?)*
	"}"
	;

Expression:
	TrueLiteral | FalseLiteral
;

TrueLiteral:
	{TrueLiteral}"true"
;

FalseLiteral:
	{FalseLiteral}"false" 
;

and Validation

	@Check
	def void checkFalse(FalseLiteral falseLiteral) {
		error("false is bad", falseLiteral, null, "FALSE_IS_BAD")
	}

and Quickfix

	@Fix("FALSE_IS_BAD")
	def makeItTrue(Issue issue, IssueResolutionAcceptor acceptor) {
		acceptor.acceptMulti(issue, 'Make It True', 'Make It True.', 'upcase.png') [
			EObject o, context |
			context.addModification(o)[
				EcoreUtil.replace(o, MyDslFactory.eINSTANCE.createTrueLiteral)
			]
		]
	}

applied to this model

model demo {
	false ; false ; false;
}

results in

model demo { true true true ;  ; ;
}

as you can see the semicolons keep dangling at the end (new literals are introduced at the beginning, and removed from the place they where without removing the ;

if i make the semicolon required

(expressions+=Expression ';')*

the result is

model demo { true true true ;  ; ;
}

@meysholdt any hints?

Start by reproducing the grammar, validation, and quickfix example from the issue, then inspect IChangeSerializer handling of replaced EObjects and unassigned semicolons. Trace how the replacement is serialized and add a regression test covering both optional and required semicolons; done means the resulting model preserves the intended separators without dangling semicolons.