Document spring-vault-core as a dependency to use the vault repository

Description:

• Spring Boot Version : 2.2.7

• Spring Cloud Version: Hoxton.SR4

Kubernetes Service Acccount based authentication doesn't work even when all the corresponding properties are specified.

application.properties:

#Server port
server.port = 8888
spring.profiles.active=vault

#Vault prod
spring.cloud.config.server.vault.host=vault.domain.org
spring.cloud.config.server.vault.scheme=https
spring.cloud.config.server.vault.backend=<backend>
spring.cloud.config.server.vault.port=443
spring.cloud.config.server.vault.profile-separator=-
spring.cloud.config.server.vault.default-key=<defaultKey>
spring.cloud.config.server.vault.authentication=KUBERNETES
spring.cloud.config.server.vault.kubernetes.role=<rolename>
spring.cloud.config.server.vault.kubernetes.kubernetes-path=kubernetes
spring.cloud.config.server.vault.kubernetes.service-account-token-file=/var/run/secrets/kubernetes.io/serviceaccount/token
spring.cloud.config.server.vault.kv-version=2
logging.level.org.springframework.web=DEBUG

Token based authentication for Vault works perfectly, but when Kubernetes Service Account based authentication is used, below error is thrown when a Get call is made to the config server

There was an unexpected error (type=Bad Request, status=400). Missing required header in HttpServletRequest: X-Config-Token

This issue gets fixed upon adding the below dependency to the project POM.

<dependency>
	<groupId>org.springframework.vault</groupId>
	<artifactId>spring-vault-core</artifactId>
</dependency>

Is this because "spring-vault-core" dependency has been marked as optional in the spring-cloud-config-server pom.xml?

However, the pom change still doesn't solve the issue completely. The first request made to config server fails. The first request error has already been reported here

Please help me out here and let me know if there there's anything I'm missing.

Read spring-cloud-config-server/pom.xml and the supplied application.properties first. Reproduce a config-server GET using Kubernetes service-account authentication, then determine whether spring-vault-core must be non-optional and how the first-request failure related to issue 1556 affects the result.