[Bug - MCP server] `McpResource.annotations` is ignored/does nothing

Bug description

The annotations property of an McpResource is ignored. It is not propagated to the client.

@McpResource(
    uri = "test://resource/{id}",
    name = "test-resource",
    annotations = @McpResource.McpAnnotations(
            audience = McpSchema.Role.ASSISTANT,
            priority = 1.0,
            lastModified = "some time"
    )
)
public String myResource() {
    return "something";
}

The only accessor of this property is

https://github.com/spring-projects/spring-ai/blob/ca666e7331c40b00d7da3c535e1a9c8e99e39995/mcp/mcp-annotations/src/main/java/org/springframework/ai/mcp/annotation/adapter/ResourceAdapter.java#L42

The only callers of that method are tests

Environment

Spring AI version: 2.0.0

Expected behavior

Properties should be sent to the client.

For lastModified specifically, the design seems wrong. It's quite unlikely that a static lastModified time will be possible. In many cases, the the property must be derived programmatically from the resource.

McpResource is also used for template resources, and for such cases, there is not a single last modified time - it depends on the resource.

Start with mcp/mcp-annotations/src/main/java/org/springframework/ai/mcp/annotation/adapter/ResourceAdapter.java at the referenced accessor, then inspect the tests that call it and trace how the resource reaches the client. Done means the McpResource annotations are propagated to the client, with the handling of lastModified clarified for resources and templates.