[GH-3171][GH-3172] Fix empty polygon orientation and GeoSeries skew flags

[jiayuasu]

Did you read the Contributor Guide?

• Yes, I have read the Contributor Rules and Contributor Development Guide

Is this PR related to a ticket?

• Yes, and the PR name follows the format [GH-XXX] my subject.

Closes #3171.
Closes #3172.

What changes were proposed in this PR?

• Treat empty Polygon and MultiPolygon inputs as vacuously true in both ST_IsPolygonCW and ST_IsPolygonCCW.
• Avoid accessing the first component of an empty MultiPolygon, and treat empty members of mixed multipolygons as neutral.
• Add common, Spark, Flink, and Snowflake coverage and document the empty-geometry behavior across all three engines.
• Accept Python and NumPy integer values for GeoSeries.skew(use_radians=...), matching GeoPandas truthiness behavior while retaining strict rejection of non-integral values.

The orientation predicates previously accessed getGeometryN(0) unconditionally for multipolygons and did not handle an empty polygon consistently. The GeoSeries method separately restricted use_radians to boolean scalar types even though GeoPandas also accepts integer boolean-like values.

Full PostGIS parity for non-polygonal inputs and geometry collections is deferred to #3174 because it changes existing predicate results and should be handled at a major-version boundary.

How was this patch tested?

• mvn -pl common -Dtest=FunctionsTest test (302 tests)
• Spark functionTestScala suite (235 tests)
• Focused Flink empty-polygon orientation test
• python -m pytest -q tests/geopandas/test_geoseries.py -k skew (20 tests)
• mvn -Dsnowflake=true -pl snowflake-tester -am -DskipTests package
• Repository pre-commit hooks

Did this PR include necessary documentation updates?

• Yes, I have updated the documentation.

[Copilot]

Pull request overview

This PR fixes edge-case handling for polygon orientation predicates across Sedona engines and aligns Sedona’s GeoPandas-compatible GeoSeries.skew(use_radians=...) behavior with GeoPandas by accepting integer “boolean-like” flags.

Changes:

• Make ST_IsPolygonCW / ST_IsPolygonCCW return true for empty POLYGON/MULTIPOLYGON inputs and avoid getGeometryN(0) on empty multipolygons.
• Expand GeoSeries.skew(use_radians=...) to accept Python/NumPy integer scalars (while still rejecting non-integral values like floats).
• Add/extend coverage (common, Spark, Flink, Snowflake, Python) and document empty-geometry semantics in SQL/Snowflake/Flink docs.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
common/src/main/java/org/apache/sedona/common/Functions.java	Fixes orientation predicate logic for empty polygons/multipolygons and removes unsafe first-element access.
common/src/test/java/org/apache/sedona/common/FunctionsTest.java	Adds unit tests covering empty polygon/multipolygon and mixed multipolygon cases.
spark/common/src/test/scala/org/apache/sedona/sql/functionTestScala.scala	Adds Spark SQL test ensuring empty polygonal geometries return true for both predicates.
flink/src/test/java/org/apache/sedona/flink/FunctionTest.java	Adds Flink SQL test for empty polygon/multipolygon orientation behavior.
snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctions.java	Adds Snowflake V1 function tests for empty polygon/multipolygon orientation behavior.
snowflake-tester/src/test/java/org/apache/sedona/snowflake/snowsql/TestFunctionsV2.java	Adds Snowflake V2 function tests for empty polygon/multipolygon orientation behavior.
python/sedona/spark/sql/st_functions.py	Updates Python SQL-function docstrings to document empty-geometry behavior consistently.
python/sedona/spark/geopandas/geoseries.py	Allows integer/NumPy-integer use_radians values and normalizes via bool(use_radians).
python/tests/geopandas/test_geoseries.py	Adds tests verifying integer use_radians parity with GeoPandas and adjusts invalid-case coverage to floats.
docs/api/sql/Geometry-Accessors/ST_IsPolygonCW.md	Documents POLYGON EMPTY / MULTIPOLYGON EMPTY returning true.
docs/api/sql/Geometry-Accessors/ST_IsPolygonCCW.md	Documents POLYGON EMPTY / MULTIPOLYGON EMPTY returning true.
docs/api/flink/Geometry-Accessors/ST_IsPolygonCW.md	Documents empty-geometry semantics for Flink docs.
docs/api/flink/Geometry-Accessors/ST_IsPolygonCCW.md	Documents empty-geometry semantics for Flink docs.
docs/api/snowflake/vector-data/Geometry-Accessors/ST_IsPolygonCW.md	Documents empty-geometry semantics for Snowflake docs.
docs/api/snowflake/vector-data/Geometry-Accessors/ST_IsPolygonCCW.md	Documents empty-geometry semantics for Snowflake docs.

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