perf: less PositionInList allocations

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[Copilot]

Copilot review overview

🟡 Changes recommended

The updated Javadoc code block uses invalid HTML nesting that may render incorrectly in generated documentation.

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Review effort: Lite
Findings: 1

Open (1)

• Fix invalid HTML nesting in Javadoc code example · New

What changed in this PR

This PR reduces runtime allocations related to list variable element position lookups by switching hot-path code from ElementPosition materialization to direct inverse lookups, and adds regression tests to ensure consistency between these APIs.

Changes:

• Replace getElementPosition(... ) instanceof PositionInList usage with getInverseSingleton(...) in FilteringValueRangeSelector to avoid allocating PositionInList.
• Simplify pinned-element filtering in ListChangeMoveSelector by delegating to ListVariableState.isPinned(...) (avoids per-candidate ElementPosition allocation).
• Add tests verifying getInverseSingleton(...) and getElementPosition(...) stay consistent, including when inverse is externalized.

File	Description
core/​src/​test/​java/​ai/​timefold/​solver/​core/​impl/​domain/​variable/​DefaultListVariableStateTest.java	Adds coverage to ensure inverse lookups and element-position reporting remain consistent across internal/externalized storage.
core/​src/​main/​java/​ai/​timefold/​solver/​core/​impl/​heuristic/​selector/​value/​decorator/​FilteringValueRangeSelector.java	Uses inverse lookups instead of element position objects on the reachability path to reduce allocations; updates Javadoc example formatting.
core/​src/​main/​java/​ai/​timefold/​solver/​core/​impl/​heuristic/​selector/​move/​generic/​list/​ListChangeMoveSelector.java	Switches pinned filtering to ListVariableState.isPinned(...) to avoid allocating element position objects per candidate.

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[Copilot]

Copilot review overview

🔵 Needs a closer look

The updated Javadoc uses invalid HTML nesting and there is avoidable allocation overhead introduced in a performance-sensitive initialization branch.

Review effort: Lite
Findings: 1

Open (1)

• Fix invalid HTML nesting in Javadoc code example

Previously missed (1)

In code that hasn't changed since last review

Avoid allocating unused unassigned value set

core/​src/​main/​java/​ai/​timefold/​solver/​core/​impl/​domain/​variable/​ListVariableStateCarrier.java:107

When shouldUnassignElements is false (first initialization with expectShadowVariablesInCorrectState() true), unassignedValueSet is still allocated at initialUnassignedCount capacity even though it is never used, which is avoidable overhead on a performance-sensitive path.

The review comments have been accepted and resolved.
In order to not let this PR stay open any longer, and considering this PR has another approving review already, I will merge as is.

[Copilot]

Copilot review overview

🔵 Needs a closer look

The updated Javadoc example in FilteringValueRangeSelector uses invalid HTML tag nesting that should be corrected to avoid doclint/Javadoc rendering issues.

Review effort: Lite
Findings: 1

Open (1)

• Fix invalid HTML nesting in Javadoc code example

[Copilot]

Copilot review overview

🔵 Needs a closer look

It changes core list-variable shadow initialization/reset semantics and selection behavior on performance-sensitive paths, warranting final human review.

Review effort: Lite
Findings: None

Resolved since last review (1)

• Fix invalid HTML nesting in Javadoc code example

[Copilot]

Copilot review overview

🟢 Approval recommended

The changes are performance-focused, maintain behavioral intent, and are backed by new tests covering key consistency and reset edge cases.

Review effort: Lite
Findings: None