fix(mcp): NPE in ListStreamsTool when stream description is null

[monrax]

Description

Handle nullable description field in ListStreamsTool.apply(). StreamDTO.description() and StreamImpl.description() are both annotated @Nullable, but the value was passed directly into Map.of() which throws NullPointerException on null values. Wrapped with Optional.ofNullable(...).orElse("") to safely default to an empty string.

Motivation and Context

When any stream has no description, the list_streams MCP tool call fails with "Tool call failed: null", making the entire tool unusable if even a single stream lacks a description.

Fixes #25214

How Has This Been Tested?

Manual testing: created a stream without a description and verified the list_streams MCP tool returns all streams successfully.

Screenshots (if appropriate):

N/A

Types of changes

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

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have requested a documentation update.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.

[bernd]

You can use Objects.requireNonNullElse(stream.getDescription(), "") to avoid the Optional object creation.

[monrax]

thanks for the feedback! I just changed it. Please take a look when you can