# Third-party code

## MapSyncer for Xaero's World Map

Everything under `src/main/java/com/mapsyncer/` and the two renderer adapters
`src/main/java/lv/janhouse/mapsyncer/render/BlockPropertyResolver.java` and
`PlaceholderBlockGetter.java` are taken from

    MapSyncer for Xaero's World Map
    https://github.com/RuoChennn/MapSyncer-for-XaeroWorldmap
    commit 116986ac17d9c18706bbbd9df7851bd365bb67f1 (2026-09-02, v1.0.4 beta)
    Copyright (c) RuoChennn and contributors
    Licensed under the GNU General Public License v3.0

That project is the reference implementation of the wire protocol this plugin
speaks and of the Xaero region-file writer. This plugin as a whole is therefore
also distributed under the GPL-3.0 (see `LICENSE`).

Local modifications to the vendored code, kept deliberately small so upstream
diffs stay readable:

- `mca/ChunkMask.java` — new: lets a conversion skip chunks nobody has
  discovered (they become "no data" tiles instead of terrain).
- `mca/convert/io/McaRegionLoader.java`, `mca/convert/RegionConversionPipeline.java`
  — overloads taking a `ChunkMask`.
- `mca/McaReader.java` — imports the plain `net.jpountz` LZ4 package that the
  Paper server already ships (upstream relocates its own copy).
- `mca/ChunkDataParser.java` — heightmap bit width uses vanilla's
  `ceillog2(height + 1)` (upstream under-counts by one for 256-high
  dimensions); accepted chunk statuses include `initialize_light`.
- `XaeroWriter.java` — moved from `com.mapsyncer.server` to `com.mapsyncer`.
- `render/BlockPropertyResolver.java`, `render/PlaceholderBlockGetter.java` —
  package moved; the cache-size constant is inlined.

Everything else in `lv.janhouse.mapsyncer` is original to this repository.

## lz4-java

LZ4-compressed region files are read through the `net.jpountz.lz4` classes the
Paper server bundles (`at.yawk.lz4:lz4-java`, Apache License 2.0). Nothing of
it is redistributed in this jar.