org.eclipse.xtext.formatting2.internal.ConflictingRegionsException: Conflicting Regions.
{{{}}}: ConditionalReplacer at offset=3063 length=33
[[[]]]: ConditionalReplacer at offset=3050 length=47
------------------------------- document snippet -------------------------------

	call
	[
	thing|something or another . chained] - too    .
	long    [[[[     for
	| {{{the
	.previous (
	line=     -1
	)}}}]]]] < same
	.
	thing
	[
--------------------------------------------------------------------------------

ISubFormatter subFormatter = (subDoc) -> {
  document.append(...); // this will produce this error. Use subDoc instead
};

document.formatConditionally(obj, subFormatter);

// wrong
document.requireFitsInLine();
document.append(...); // this will produce this error. requireFitsInLine already reserves the entirety of document so no other formatters can touch it

// correct
document = document.requireFitsInLine();
document.append(...);