From cca35b08a203abc3356e29eee5a610177253b469 Mon Sep 17 00:00:00 2001
From: arimu1 <19286898+arimu1@users.noreply.github.com>
Date: Sat, 26 Sep 2026 10:47:20 +0700
Subject: [PATCH] fix(jts): align GEOMETRYCOLLECTION with MULTIPOLYGON WKT
 parse

JtsMultiShapeBuilder re-wrapped homogeneous children via makeShapeFromGeometry,
which re-validated geometries that multi* builders already accept via makeShape.
Return a lone child unchanged and use makeShape for homogeneous Multi* merges.

Fixes #232

Signed-off-by: arimu1 <19286898+arimu1@users.noreply.github.com>
---
 .../spatial4j/shape/jts/JtsShapeFactory.java          | 11 ++++++++++-
 .../spatial4j/io/JtsWktShapeParserTest.java           | 11 +++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/locationtech/spatial4j/shape/jts/JtsShapeFactory.java b/src/main/java/org/locationtech/spatial4j/shape/jts/JtsShapeFactory.java
index f162051dc..50edd6839 100755
--- a/src/main/java/org/locationtech/spatial4j/shape/jts/JtsShapeFactory.java
+++ b/src/main/java/org/locationtech/spatial4j/shape/jts/JtsShapeFactory.java
@@ -443,7 +443,16 @@ public Shape build() {
         last = s.getClass();
       }
 
-      return makeShapeFromGeometry(geometryFactory.buildGeometry(geoms));
+      if (shapes.size() == 1) {
+        return shapes.get(0);
+      }
+
+      Geometry combined = geometryFactory.buildGeometry(geoms);
+      // Homogeneous collections become Multi* types; match multi* builders (no re-validate).
+      if (combined.getClass().equals(GeometryCollection.class)) {
+        return makeShapeFromGeometry(combined);
+      }
+      return makeShape(combined);
     }
   }
 
diff --git a/src/test/java/org/locationtech/spatial4j/io/JtsWktShapeParserTest.java b/src/test/java/org/locationtech/spatial4j/io/JtsWktShapeParserTest.java
index 429d26e92..c755c66a1 100644
--- a/src/test/java/org/locationtech/spatial4j/io/JtsWktShapeParserTest.java
+++ b/src/test/java/org/locationtech/spatial4j/io/JtsWktShapeParserTest.java
@@ -138,6 +138,17 @@ public void testLineStringDateline() throws ParseException {
     assertEquals(30, s.getBoundingBox().getWidth(), 0.0 );
   }
 
+  @Test
+  public void selfIntersectingMultiPolygonSameInGeometryCollection() throws ParseException {
+    WKTReader geoReader = (WKTReader) JtsSpatialContext.GEO.getFormats().getWktReader();
+    String multi =
+        "MULTIPOLYGON (((5 5, 10 5, 10 10, 5 5)), ((6 6, 10 5, 10 10, 6 6)))";
+    String collection =
+        "GEOMETRYCOLLECTION ( MULTIPOLYGON (((5 5, 10 5, 10 10, 5 5)), ((6 6, 10 5, 10 10, 6 6))) )";
+    geoReader.parse(multi);
+    geoReader.parse(collection);
+  }
+
   @Test
   public void testWrapTopologyException() throws Exception {
     //test that we can catch ParseException without having to detect TopologyException too