Kotlin properties in Thymeleaf templates with Spring EL

I have a class with the property

var isDone: Boolean

but if I reference it in a Thymeleaf template

<span th:text="${task.isDone}></span>

I get the following error

org.springframework.expression.spel.SpelEvaluationException: EL1008E: Property or field ‘isDone’ cannot be found on object of type …

I’m wondering why it doesn’t work, since the Java Bean standard allows boolean methods starting with is. The compiler generates the following method:

public final boolean isDone() {
  return this.isDone;

Looking at this method I would expect it to work, but Spring EL seems to expect isIsDone.

It works if I use only done in the tempalte:

<span th:text="${task.done}></span>

… or if I name the property isIsDone and use isDone in the template.

Why does isDone doesn’t work although it meets the bean convention?

Is there a simple solution (like the Kotlin extensions for Jackson)?