[bug] NPE occurs for StringType when column value is null. (#141) #343

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	---
	name: Build Extensions
	on:
	pull_request:
	push:

	env:
	MVN_OPT: --no-transfer-progress

	jobs:
	build-extension:
	name: "Build Extensions"
	runs-on: ubuntu-latest
	defaults:
	run:
	shell: bash
	steps:
	- name: Checkout
	uses: actions/checkout@v3

	- name: Setup java
	uses: actions/setup-java@v3
	with:
	distribution: temurin
	java-version: '8'
	cache: 'maven'

	- name: Build spark connector v2
	run: \|
	cd spark-doris-connector && mvn clean package ${MVN_OPT} \
	-Dspark.version=2.3.4 \
	-Dscala.version=2.11 \
	-Dspark.major.version=2.3

	- name: Build spark connector v3
	run: \|
	cd spark-doris-connector && mvn clean package ${MVN_OPT} \
	-Dspark.version=3.1.2 \
	-Dscala.version=2.12 \
	-Dspark.major.version=3.1

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