this check, for debugging and experimenting purposes.

<!-- CL 473495 -->
When building a dynamically linked ELF binary (including PIE binary), the

    val sharedIdentities: ReadIdentities

    override val isolate: ReadIsolate

    val classLoader: ClassLoader

    fun beanStateReaderFor(beanType: Class<*>): BeanStateReader

    /**
     * When in immediate mode, [read] calls are NOT suspending.
     * Useful for bridging with non-suspending serialization protocols such as [java.io.Serializable].
     */