HostStubGen: Fix minor bug

 * Base class for an [OutputFilter] that uses another filter as a fallback.

 */

abstract class DelegatingFilter(

        // fallback shouldn't be used by subclasses, so make it private.

        // fallback shouldn't be used by subclasses directly, so make it private.

        // They should instead be calling into `super` or `outermostFilter`.

        private val fallback: OutputFilter

) : OutputFilter() {

        fallback.outermostFilter = this

    }

    /**

     * Returns the outermost filter in a filter chain.

     *

     * When methods in a subclass needs to refer to a policy on an item (class, fields, methods)

     * that are not the "subject" item -- e.g.

     * in [ClassWidePolicyPropagatingFilter.getPolicyForField], when it checks the

     * class policy -- [outermostFilter] must be used, rather than the super's method.

     * The former will always return the correct policy, but the later won't consult outer

     * filters than the current filter.

     */

    override var outermostFilter: OutputFilter = this

        get() = field

        set(value) {

            field = value

            // Propagate the inner filters.

            // Propagate to the inner filters.

            fallback.outermostFilter = value

        }

        val fallback = super.getPolicyForField(className, fieldName)

        val cn = classes.getClass(className)

        val classPolicy = super.getPolicyForClass(className)

        val classPolicy = outermostFilter.getPolicyForClass(className)

        log.d("Class ${cn.name} Class policy: $classPolicy")

        if (classPolicy.policy.needsInImpl) {