Allow custom or numeric request ID generation (Snowflake MCP server rejects string IDs)

Expected Behavior

The Java SDK should provide a way to configure how request IDs are generated. This could include:

• A public interface or callback for supplying a custom RequestIdGenerator.
• Configuration options to choose between UUID-based, string-based, or numeric-only IDs.

This would help support MCP servers that require strict numeric IDs or forbid UUID/string-based request IDs.

Current Behavior

Currently, the Java SDK:

• Uses a private generateRequestId() method.
• Uses an internal private counter.
• Produces UUID-counter formatted IDs like "62d0970d-0".
• Provides no public extension point to override or customize ID generation.

This causes compatibility issues with MCP servers (such as Snowflake's MCP implementation) that accept only numeric IDs.

Example (hypothetical API):

McpClient client = McpClient.builder()
    .withRequestIdGenerator(() -> String.valueOf(counter.incrementAndGet()))
    .build();

Context

When integrating with the Snowflake MCP server, requests are rejected because the Java SDK always generates UUID-based IDs.

Workarounds include:

• Implementing a custom transport such as SimpleHttpTransport.
• Remapping request and response IDs manually.

These solutions work but duplicate SDK logic and introduce unnecessary complexity. Providing a built-in, configurable ID generation mechanism would make the SDK more flexible and easier to use.

先追蹤 private generateRequestId() 方法和內部計數器，然後檢查 McpClient builder 和 transport 如何傳遞請求 ID。完成的條件是 SDK 提供可設定的產生器，能夠產生數值 ID，同時保留現有行為；確認請求 ID 和回應 ID 仍然相容。