Evolving Spring Vault: Introducing VaultClient

Spring Vault 4.1 introduces VaultClient and ReactiveVaultClient as modern replacements for the template-based API. The new fluent interface enforces relative path handling to prevent security issues, eliminates confusion between Vault and platform-specific HTTP clients, and aligns with Spring's HTTP client evolution. Built on RestClient/WebClient primitives, it provides better abstraction while preparing for RestTemplate deprecation in Spring Framework 7.1. Migration involves moving customizations from RestTemplateCustomizer to VaultClientCustomizer, with future plans for PKI integration with SSL bundles and database credential rotation.