SEP-2468: Recommend Issuer (iss) Parameter in MCP Auth Responses

[localden]

Tracking implementation of SEP-2468 for the 2026-07-28 MCP spec release.

[Kehrlann]

Authorization is handled outside of the SDK itself, as per Architecture and design decisions. Keeping open until we have at least one implementation demonstrating this implementation.

Tracking issues in Spring's MCP-Security:

• Client side: MCP Client: SEP-2468: Recommend Issuer (iss) Parameter in MCP Auth Responses spring-ai-community/mcp-security#81
• Auth server side: Authorization Server: SEP-2468: Recommend Issuer (iss) Parameter in MCP Auth Responses spring-ai-community/mcp-security#82