fix: JSON schema union types are no longer conformed into boolean values

singer_sdk/helpers/_typing.py

@@ -279,6 +279,17 @@ def is_boolean_type(property_schema: dict) -> bool | None:
     return False
 
 
+def _is_exclusive_boolean_type(property_schema: dict) -> bool:
+    if "type" not in property_schema:
+        return False
+
+    return (
+        property_schema["type"] == "boolean"
+        or property_schema["type"] == ["boolean"]
+        or set(property_schema["type"]) == {"boolean", "null"}
+    )
+
+
 def is_integer_type(property_schema: dict) -> bool | None:
     """Return true if the JSON Schema type is an integer or None if detection fails."""
     if "anyOf" not in property_schema and "type" not in property_schema:
@@ -523,6 +534,6 @@ def _conform_primitive_property(  # noqa: PLR0911
     if isinstance(elem, bytes):
         # for BIT value, treat 0 as False and anything else as True
         return elem != b"\x00" if is_boolean_type(property_schema) else elem.hex()
-    if is_boolean_type(property_schema):
+    if _is_exclusive_boolean_type(property_schema):
         return None if elem is None else elem != 0
     return elem

tests/core/test_typing.py

@@ -313,7 +313,16 @@ def test_conform_primitives():
 
     assert _conform_primitive_property(None, {"type": "boolean"}) is None
     assert _conform_primitive_property(0, {"type": "boolean"}) is False
+    assert (
+        _conform_primitive_property(
+            0, {"anyOf": [{"type": "boolean"}, {"type": "integer"}]}
+        )
+        == 0
+    )
+    assert _conform_primitive_property(0, {"type": ["boolean", "integer"]}) == 0
     assert _conform_primitive_property(1, {"type": "boolean"}) is True
+    assert _conform_primitive_property(1, {"type": ["boolean", "null"]}) is True
+    assert _conform_primitive_property(1, {"type": ["boolean"]}) is True
 
 
 @pytest.mark.parametrize(