build: set vaadin dependency as optional #24

	# This workflow will build a Java project with Maven, and cache/restore any dependencies to improve the workflow execution time
	# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-java-with-maven

	# This workflow uses actions that are not certified by GitHub.
	# They are provided by a third-party and are governed by
	# separate terms of service, privacy policy, and support
	# documentation.

	name: Java CI with Maven

	on:
	push:
	branches: [ "master" ]
	pull_request:
	branches: [ "master" ]

	jobs:
	build-vaadin14:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v3
	- name: Set up JDK
	uses: actions/setup-java@v3
	with:
	java-version: '8'
	distribution: 'temurin'
	cache: maven
	- name: Build (Vaadin 14)
	run: mvn -B package --file pom.xml

	build-vaadin23:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v3
	- name: Set up JDK
	uses: actions/setup-java@v3
	with:
	java-version: '11'
	distribution: 'temurin'
	cache: maven
	- name: Build (Vaadin 23)
	run: mvn -B package --file pom.xml -Pv23

	build-vaadin24:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v3
	- name: Set up JDK
	uses: actions/setup-java@v3
	with:
	java-version: '17'
	distribution: 'temurin'
	cache: maven
	- name: Build (Vaadin 24)
	run: mvn -B package --file pom.xml -Pv24

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