spring boot整合elasticsearch，启动报错，null val?400报错

Caused by: java.lang.NullPointerException: null value in entry: path.home=null
	at com.google.common.collect.CollectPreconditions.checkEntryNotNull(CollectPreconditions.java:33)
	at com.google.common.collect.ImmutableMap.entryOf(ImmutableMap.java:135)
	at com.google.common.collect.ImmutableSortedMap.fromEntries(ImmutableSortedMap.java:282)
	at com.google.common.collect.ImmutableSortedMap.copyOfInternal(ImmutableSortedMap.java:275)
	at com.google.common.collect.ImmutableSortedMap.copyOf(ImmutableSortedMap.java:206)
	at org.elasticsearch.common.settings.Settings.<init>(Settings.java:83)
	at org.elasticsearch.common.settings.Settings$Builder.build(Settings.java:1209)
	at org.elasticsearch.node.NodeBuilder.settings(NodeBuilder.java:84)
	at org.springframework.data.elasticsearch.client.NodeClientFactoryBean.afterPropertiesSet(NodeClientFactoryBean.java:73)
	at org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchAutoConfiguration.createNodeClient(ElasticsearchAutoConfiguration.java:75)
	at org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchAutoConfiguration.createClient(ElasticsearchAutoConfiguration.java:69)
	at org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchAutoConfiguration.elasticsearchClient(ElasticsearchAutoConfiguration.java:57)
	... 52 more

 
最近在做一个实验，就是spring-boot整合es，
es版本 是2.4.1

spring.data.elasticsearch 版本2.0.2
纠结点在
path.home=null
这里，但是我老是搞不明白到底要怎么做