[Bonajo]

Summary

Adds what the sorting assignment needs for a fifth, linear-time sorter (LSD radix sort):

• KeySorter<T>: Queue<T> sort(Queue<T> queue, ToIntFunction<T> key). It sorts on a non-negative int key instead of a Comparator, is stable, and throws IllegalArgumentException for a negative key.
• SortKind.RADIX.
• SorterConfiguration.usesKeySorter() and getKeySorter() as default methods (false / null), so existing configurations keep compiling.

The version goes to 1.3.0.

After merging

Create release v1.3.0, so the deploy workflow publishes the package and the javadoc. The solution PR of alda_sorting_solution depends on this version.

Testing

mvn install and mvn compile javadoc:javadoc pass with no javadoc warnings. The solution's teacher tests (140) pass against the locally installed 1.3.0.

Fixes from the consistency review

• The javadoc of getQueue() and getSorter() now says what they return for special configurations: getQueue() returns null for a priority queue configuration; getSorter() returns a pass-through sorter for a priority queue configuration and null for a key sorter.

[Copilot]

🟢 Approval recommended

No active review issues were identified for the key-based radix-sort API extension.

No open issues 🎉

What changed in this PR

Extends the sorting service API to support the assignment’s fifth sorter, LSD radix sort, through a key-based sorting contract rather than an implementation.

Changes:

• Adds KeySorter<T> with stable sorting, non-negative integer keys, and a same-queue return contract.
• Adds SortKind.RADIX and backward-compatible default methods for key-sorter configurations.
• Bumps the package version to 1.3.0 for the dependent solution release.

File	Description
src/​main/​java/​sortingservice/​SortKind.java	Adds the RADIX enum value.
src/​main/​java/​sortingservice/​SorterConfiguration.java	Adds default usesKeySorter() and getKeySorter() methods.
src/​main/​java/​sortingservice/​KeySorter.java	Defines the key-based sorting interface and its contract.
pom.xml	Updates the package version to 1.3.0.

_{Review effort: Balanced}