Why spring ResourceUtils getFile can't read file inside jar archive? - spring

Question

In my project I have to use implementation group: 'org.springframework.cloud', name: 'spring-cloud-gcp-starter-sql-postgresql' gradle dependency. and this dependency requires auth_key.json with required google credentials to access google cloud SQL.
This properties looks like:
spring.cloud.gcp.credentials.location: 'classpath:auth_key.json'
And after gradle build I got jar file with all file resources inside, including this auth_key.json and on startup I got an error:
java.io.FileNotFoundException: class path resource [auth_key.json] cannot be resolved to absolute file path because it does not reside in the file system: jar:file:/Users/yuriy/DEVELOPMENT/BACKEND/uttr-tag-poc/build/libs/uttr-tag-poc-0.0.1-SNAPSHOT.jar!/BOOT-INF/classes!/auth_key.json
at org.springframework.util.ResourceUtils.getFile(ResourceUtils.java:217) ~[spring-core-5.3.6.jar!/:5.3.6]
at org.springframework.core.io.AbstractFileResolvingResource.getFile(AbstractFileResolvingResource.java:154) ~[spring-core-5.3.6.jar!/:5.3.6]
at org.springframework.cloud.gcp.autoconfigure.sql.GcpCloudSqlAutoConfiguration$CloudSqlDataSourcePropertiesConfiguration.setCredentialsFileProperty(GcpCloudSqlAutoConfiguration.java:222) ~[spring-cloud-gcp-autoconfigure-1.2.8.RELEASE.jar!/:1.2.8.RELEASE]
at org.springframework.cloud.gcp.autoconfigure.sql.GcpCloudSqlAutoConfiguration$CloudSqlDataSourcePropertiesConfiguration.cloudSqlDataSourceProperties(GcpCloudSqlAutoConfiguration.java:181) ~[spring-cloud-gcp-autoconfigure-1.2.8.RELEASE.jar!/:1.2.8.RELEASE]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.3.6.jar!/:5.3.6]
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:653) ~[spring-beans-5.3.6.jar!/:5.3.6]
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:638) ~[spring-beans-5.3.6.jar!/:5.3.6]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1334) ~[spring-beans-5.3.6.jar!/:5.3.6]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.3.6.jar!/:5.3.6]
and it tells that spring can't read file inside jar archive. I already got such errors before when accessing files in resource location, and solve them by using code like:
public final class ResourcesUtil {
public static InputStream getResourceAsStream(String resourcePath){
return ResourcesUtil.class.getClassLoader().getResourceAsStream(resourcePath);
}
}
But here I don't know how to take this approach, because this file reads by spring. And I don't know the way how do read this file manually.
Another strange thing is that this property works fine:
spring.liquibase.change-log: 'classpath:/db/changelogs/changelog.xml'
and spring (or liquibase) can read this file, that also locates in jar file in the same resource directory.