filter/Filter: Flush() returns empty span, not nullptr #359

	---
	on:
	workflow_dispatch:
	push:
	paths-ignore:
	- 'build/**'
	- 'doc/**'
	- 'subprojects/**'
	- 'systemd/**'
	- 'win32/**'
	branches:
	- master
	pull_request:
	paths-ignore:
	- 'build/**'
	- 'doc/**'
	- 'subprojects/**'
	- 'systemd/**'
	- 'win32/**'
	branches:
	- master

	permissions:
	contents: read # to fetch code (actions/checkout)

	jobs:
	build-android:
	runs-on: ubuntu-24.04
	steps:
	- id: checkout
	uses: actions/checkout@v4

	- name: Install dependencies
	run: \|
	sudo apt-get update
	sudo apt-get install -y --no-install-recommends \
	meson \
	ccache \
	quilt

	- id: cache-ccache
	uses: hendrikmuhs/ccache-action@v1
	with:
	key: android

	# todo: remove once NDK 27 is out of beta
	- name: Install Beta NDK
	run: \|
	echo y \| ${ANDROID_SDK_ROOT}/cmdline-tools/latest/bin/sdkmanager "ndk;27.0.12077973"

	- name: Build
	run: \|
	mkdir -p output/android
	cd ./output/android
	../../android/build.py $ANDROID_SDK_ROOT $ANDROID_SDK_ROOT/ndk/27.0.12077973 arm64-v8a \
	--buildtype=debugoptimized -Db_ndebug=true \
	-Dwrap_mode=forcefallback

	cd -
	cd ./android
	export JAVA_HOME=$JAVA_HOME_17_X64
	./gradlew assembleDebug

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