perf: improve hashing performance

[triceo]

• Change hashCode() implementation in types which are commonly used in hashing (such as pairs and composite keys) due to the default methods for records doing far too much work.
• The pattern used in these methods now is the same as you'd find in Objects.hashCode(...) and Objects.equals(...), with the assumption that the JDK project optimized those. We avoid actually calling these JDK methods due to https://bugs.openjdk.org/browse/JDK-8015417.
• Also brought value ranges in line with this convention.

[Copilot]

Pull request overview

This PR optimizes hashing performance across commonly used data structures by replacing JDK utility methods with custom implementations that avoid known performance issues. The changes target types frequently used as hash keys (Pair, Triple, Quadruple, composite keys) and value ranges.

Key changes:

• Replace Objects.hash() and Objects.hashCode() with direct hashCode calculations to avoid array allocation and performance bugs
• Standardize initial hash seed value from 7 to 1 across all implementations
• Leverage @NullMarked annotations to remove redundant null checks

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 28 comments.

Show a summary per file

File	Description
Pair.java, Triple.java, Quadruple.java	Optimized equals/hashCode for tuple classes with manual null-safe implementations
BiCompositeKey.java	Updated composite key hashing to avoid Objects utility methods
MegaCompositeKey.java	Changed to use Arrays.deepEquals/deepHashCode for proper array comparison
TemporalValueRange.java	Removed null checks, updated equals/hashCode, simplified annotations
IntValueRange.java, LongValueRange.java	Updated primitive wrapper range classes with optimized hashing
BigIntegerValueRange.java, BigDecimalValueRange.java	Improved hashing for big number ranges
BooleanValueRange.java	Simplified contains() logic and removed unnecessary Boolean.valueOf()
SetValueRange.java, ListValueRange.java	Updated collection-based ranges with optimized equals/hashCode
CompositeCountableValueRange.java, NullAllowingCountableValueRange.java	Improved composite range hashing
DoubleValueRange.java	Simplified hashCode calculation (though inconsistent with other changes)
EmptyValueRange.java	Changed singleton hashCode from 7 to 0
TestdataObjectEquals.java	Simplified test class hashCode
TemporalValueRangeTest.java	Removed null validation tests (covered by @NullMarked)

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[Copilot]

Pull request overview

Copilot reviewed 19 out of 19 changed files in this pull request and generated 1 comment.

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[sonarqubecloud]

Quality Gate failed

Failed conditions
37.9% Coverage on New Code (required ≥ 70%)
5.6% Duplication on New Code (required ≤ 5%)

See analysis details on SonarQube Cloud

[Copilot]

Pull request overview

Copilot reviewed 20 out of 20 changed files in this pull request and generated 3 comments.

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