See gh-22510

Includes removal of outdated Spring 1.2/2.0 references.

Closes gh-22429

Closes gh-22510

Closes gh-22507

Prior to this commit, repeated calls to `DataBuffer.write(CharSequence,
Charset)` would not write the given chars to the expected position in
the original buffer.

This commit fixes that by writing to the `outBuffer.position()`, offset
by the current `DataBuffer.writePosition()`.

Fixes gh-22484

* pr/22500:
  Fix typo in `my-property'

Closes gh-22500

Closes gh-22416

Closes gh-22491

Closes gh-22409

* pr/22482:
  Polish

Closes gh-22482

Closes gh-22473

Closes gh-22468

Closes gh-22449

Closes gh-22444

Closes gh-22426

Closes gh-22435

Prior to this commit, the negotiated content-type during the request
mapping phase would be kept as the response content-type header; this
information is used when rendering the error response and prevents a new
round of content negotiation to choose the media type that fits best.

This commit removes the response content type information at the
beginning of the error handling phase.

Fixes gh-22452

Closes gh-22412

Closes gh-22419

Closes gh-22410

* pr/22385:
  Polish "Ensure indexer gracefully handle missing meta annotations"
  Ensure indexer gracefully handle missing meta annotations

Closes gh-22385

See gh-22385