To handle the ref (Prompt/Resource) of the Complete request reliably using Jackson polymorphic deserialization, we added type metadata (@JsonTypeInfo / @JsonSubTypes) to CompleteReference.

I also unified the server’s completion parameter parsing by replacing manual Map parsing with jsonMapper.convertValue(..., CompleteRequest.class).

Additionally, through request structure validation, cases where ref == null now fail explicitly.

Motivation and Context

While other McpSchemas specify JsonTypes, this one doesn't, leading to an error. While using this SDK, I discovered this.

I couldn't find a reason why CompleteReference was not being handled, so I'm posting a PR, deeming it an omission.

How Has This Been Tested?

i wrote some Unit test and do Integration test in local device

Breaking Changes

nop

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• [ x My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context