v2.0.0-M3

What's Changed

• feat!: enforce required MCP spec fields in McpSchema; lenient wire deserialization by @chemicL #928
• Validate message endpoint in SSE client transport by @Kehrlann in #943
• DefaultSseMessageEndpointValidator allows same-origin message endpoints by @Kehrlann in #946
• feat: validate embedded JSON Schema documents against 2020-12 meta-schema (SEP-1613) by @chemicL in #949
• Deprecate SSE transports by @Kehrlann in #950
• feat: Add SEP-973 icons and metadata support by @sainathreddyb in #912

Breaking changes

• PromptReference.equals/hashCode now key on name only (previously derived from identifier()+type()). Two refs with the same name but different titles now compare equal — code using PromptReference as a map/set key should be audited.
• PromptReference's compact constructor pins type to "ref/prompt" and logs a WARN if the caller supplies a different non-null value. The legacy two-arg PromptReference(String type, String name) constructor remains deprecated.
• ResourceReference's record components are reduced from (type, uri) to (uri) — positional construction breaks. The legacy ResourceReference(String type, String uri) constructor stays deprecated and ignores type.
• CompleteReference.identifier() is deprecated and now returns null via a default method on the interface.

New Contributors

• @sainathreddyb made their first contribution in #912

Full Changelog: v2.0.0-M2...v2.0.0-M3