In Spring Boot I attempt to inject a boolean value to an instance variable from an enviroment property which is set (`enabled=true`).

```
@Value("${enabled}")
private boolean enabled;

```

However Spring cannot resolve this for some reason and reports:

```
Caused by: java.lang.IllegalArgumentException: Invalid boolean value [${enabled}]

```

It seems like it does not replace expression `${enabled}` with the property value.

What needs to be set ? Why doesn't work this by default ?