[code_assets] [data_assets] Document absolute paths

[dcharkes]

Closes: #2711

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:code_assets	0.19.9	ready to publish	code_assets-v0.19.9
package:data_assets	0.19.4	ready to publish	data_assets-v0.19.4
package:ffi	2.1.5-wip	WIP (no publish necessary)
package:hooks	0.20.4	already published at pub.dev
package:hooks_runner	0.23.1	already published at pub.dev
package:native_toolchain_c	0.17.2	already published at pub.dev
package:swift2objc	0.1.0	already published at pub.dev
package:swiftgen	0.1.1	already published at pub.dev

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

[github-actions]

PR Health

Breaking changes ⚠️

Package	Change	Current Version	New Version	Needed Version	Looking good?
code_assets	None	0.19.8	0.19.9	0.19.8	✔️
data_assets	Breaking	0.19.3	0.19.4	0.20.0 Got "0.19.4" expected >= "0.20.0" (breaking changes)	⚠️

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Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

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API leaks ✔️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbol	Leaking sources

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License Headers ✔️

// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

Files
no missing headers

All source files should start with a license header.

Unrelated files missing license headers

Files
pkgs/objective_c/lib/src/ns_input_stream.dart

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[coveralls]

coverage: 82.001% (-10.0%) from 91.972%
when pulling ffc989d on add-assets-doc
into f7c7d52 on main.

[dcharkes]

I believe this should not be a breaking change for data assets:

• extension method widening a parameter should not be a breaking change bmw-tech/dart_apitool#251

[goderbauer]

LGTM