[Java] add missing nullable judgement when required property is true #1891

	name: Gradle tests (Java samples)

	on:
	push:
	paths:
	- 'samples/client/petstore/java/**'
	- 'samples/openapi3/client/petstore/java/**'
	pull_request:
	paths:
	- 'samples/client/petstore/java/**'
	- 'samples/openapi3/client/petstore/java/**'
	env:
	GRADLE_VERSION: 8.7

	jobs:
	build:
	name: Gradle tests
	runs-on: ubuntu-latest
	container: gradle:jdk11
	strategy:
	fail-fast: true
	matrix:
	sample:
	- samples/openapi3/client/extensions/x-auth-id-alias/java/jersey2-java8
	- samples/openapi3/client/petstore/java/jersey2-java8-special-characters
	- samples/openapi3/client/petstore/java/jersey2-java8
	- samples/client/petstore/java/jersey2-java8-localdatetime
	- samples/client/petstore/java/jersey2-java8
	- samples/client/petstore/java/okhttp-gson
	- samples/client/petstore/java/okhttp-gson-group-parameter
	- samples/client/petstore/java/webclient-swagger2
	steps:
	- uses: actions/checkout@v4
	- uses: actions/setup-java@v4
	with:
	distribution: 'temurin'
	java-version: 11
	# Cache Gradle Dependencies
	- name: Setup Gradle Dependencies Cache
	uses: actions/cache@v4
	with:
	path: ~/.gradle/caches
	key: ${{ runner.os }}-gradle-caches-${{ hashFiles('*/.gradle', '*/.gradle.kts') }}

	# Cache Gradle Wrapper
	- name: Setup Gradle Wrapper Cache
	uses: actions/cache@v4
	with:
	path: ~/.gradle/wrapper
	key: ${{ runner.os }}-gradle-wrapper-${{ hashFiles('**/gradle/wrapper/gradle-wrapper.properties') }}

	- name: Build
	working-directory: ${{ matrix.sample }}
	run: /bin/sh gradlew build -x test

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