Fix signs displaying JSON text on Minecraft 1.21.5+

[twme-ai]

Overview

Fixes #3379

Description

Minecraft 1.21.5 changed the representation of text components in sign NBT. A string now represents a literal
text component instead of JSON-encoded text. SignBlock continued wrapping each line in JSON inside the NBT
string, which caused commands such as //set spruce_sign to display the JSON source on the sign.

This change preserves the JSON-in-string representation before Minecraft 1.21.5 and writes literal strings on
Minecraft 1.21.5 and newer. It also uses the version-appropriate empty value when constructing signs or loading
incomplete sign NBT.

Regression tests cover Minecraft 1.21.4, the 1.21.5 format boundary, 1.21.10, 1.21.11, and 26.1.2.

Testing

• ./gradlew :worldedit-core:check --no-configure-on-demand
• Paper integration tests on 1.21.4, 1.21.5, 1.21.10, 1.21.11, and 26.1.2

Submitter Checklist

• Make sure you are opening from a topic branch (/feature/fix/docs/ branch (right side)) and not your main branch.
• Ensure that the pull request title represents the desired changelog entry.
• New public fields and methods are annotated with @since TODO.
• I read and followed the contribution guidelines.

[Copilot]

Pull request overview

Updates legacy SignBlock NBT serialization to account for Minecraft 1.21.5’s change where sign text NBT strings are treated as literal components (not JSON-in-string), preventing signs placed via commands like //set spruce_sign from showing JSON source on 1.21.5+.

Changes:

• Make SignBlock write JSON-in-string text for < 1.21.5 and literal strings for >= 1.21.5, including version-appropriate empty defaults.
• Add regression tests covering multiple data versions around the 1.21.5 boundary and newer versions.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
worldedit-core/src/legacy/java/com/sk89q/worldedit/blocks/SignBlock.java	Switch sign text encoding/empties based on data version to match 1.21.5+ semantics.
worldedit-core/src/test/java/com/sk89q/worldedit/blocks/SignBlockTest.java	Add tests validating JSON vs literal sign message serialization across multiple versions.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

[dordsor21]

Not actually sure we support < 1.20 anymore - don't need to support legacy anymore?

[twme-ai]

Addressed in f4e1b07 by removing the pre-1.20 Text1-Text4 NBT path. The 1.21.5 JSON/literal text boundary remains, and the pre-1.21.5 test now also covers the minimum supported 1.21 data version.