I've got an error message that I don't understand:

val sqlServerDataSource = SQLServerDataSource()
        sqlServerDataSource.url = myUrl
        sqlServerDataSource.user = myUser
        sqlServerDataSource.password = myPassword

The error is:

Cannot access 'password': it is public/*package*/ for synthetic extension in '<library Maven: com.microsoft.sqlserver:mssql-jdbc:10.2.0.jre17>'

There is no error on url or user; only on password. If I replace it with

sqlServerDataSource.setPassword(myPassword)

it works. But why can't I use the property syntax, and what exactly does the error message mean, and why only password has this error?

It's definitely a weird visibility way sqlServerDataSource uses since it's literally impossible to recreate the same scenario in kotlin; this the field cannot be mapped properly to kotlin accessibility

https://kotlinlang.org/docs/java-interop.html#getters-and-setters

Note that, if the Java class only has a setter, it isn't visible as a property in Kotlin because Kotlin doesn't support set-only properties.

the Java functions are always accessible (up to visibility) even when Kotlin synthesizes a property