Extraneous warnings related to `JdbcSqlServerDialect`.

Add tests for R2DBC types as well.

Closes #2147

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/JdbcCustomConversions.java

@@ -22,6 +22,10 @@ import java.util.List;
 import org.springframework.core.convert.converter.GenericConverter.ConvertiblePair;
 import org.springframework.data.convert.CustomConversions;
 import org.springframework.data.jdbc.core.mapping.JdbcSimpleTypes;
+import org.springframework.data.mapping.model.SimpleTypeHolder;
+import org.springframework.data.relational.core.dialect.Dialect;
+import org.springframework.lang.Contract;
+import org.springframework.util.Assert;
 
 /**
  * Value object to capture custom conversion. {@link JdbcCustomConversions} also act as factory for

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/dialect/JdbcSqlServerDialect.java

@@ -22,6 +22,7 @@ import java.time.OffsetDateTime;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Set;
 
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.data.convert.ReadingConverter;
@@ -33,12 +34,20 @@ import org.springframework.data.relational.core.dialect.SqlServerDialect;
  * @author Jens Schauder
  * @author Christoph Strobl
  * @author Mikhail Polivakha
+ * @author Mark Paluch
  * @since 2.3
  */
 public class JdbcSqlServerDialect extends SqlServerDialect implements JdbcDialect {
 
 	public static final JdbcSqlServerDialect INSTANCE = new JdbcSqlServerDialect();
 
+	private static final Set<Class<?>> SIMPLE_TYPES = Set.of(DateTimeOffset.class);
+
+	@Override
+	public Set<Class<?>> simpleTypes() {
+		return SIMPLE_TYPES;
+	}
+
 	@Override
 	public Collection<Object> getConverters() {
 

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/dialect/JdbcPostgresDialectUnitTests.java

@@ -17,7 +17,12 @@ package org.springframework.data.jdbc.core.dialect;
 
 import static org.assertj.core.api.Assertions.*;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
 import org.postgresql.geometric.PGbox;
 import org.postgresql.geometric.PGcircle;
 import org.postgresql.geometric.PGlseg;
@@ -26,28 +31,58 @@ import org.postgresql.geometric.PGpoint;
 import org.postgresql.geometric.PGpolygon;
 import org.postgresql.util.PGobject;
 
+import org.springframework.data.convert.CustomConversions;
+import org.springframework.data.jdbc.core.convert.JdbcCustomConversions;
+import org.springframework.data.jdbc.core.mapping.JdbcSimpleTypes;
+import org.springframework.data.mapping.model.SimpleTypeHolder;
+import org.springframework.data.relational.core.dialect.Dialect;
+
 /**
  * Unit tests for {@link JdbcPostgresDialect}.
  *
  * @author Jens Schauder
+ * @author Mark Paluch
  */
-public class JdbcPostgresDialectUnitTests {
+class JdbcPostgresDialectUnitTests {
 
 	@Test // GH-1065
 	void pgobjectIsConsideredSimple() {
 		assertThat(JdbcPostgresDialect.INSTANCE.simpleTypes()).contains(PGobject.class);
 	}
 
-	@Test // GH-1065
-	void geometricalTypesAreConsideredSimple() {
+	@ParameterizedTest // GH-1065, GH-2147
+	@MethodSource("simpleTypes")
+	void simpleTypesAreConsideredSimple(Class<?> type) {
+
+		JdbcCustomConversions conversions = createCustomConversions(JdbcPostgresDialect.INSTANCE);
+
+		assertThat(conversions.isSimpleType(type)).isTrue();
+		assertThat(conversions.getSimpleTypeHolder().isSimpleType(type)).isTrue();
+	}
 
-		assertThat(JdbcPostgresDialect.INSTANCE.simpleTypes()).contains( //
-				PGpoint.class, //
+	static List<Class<?>> simpleTypes() {
+		return List.of(PGpoint.class, //
 				PGbox.class, //
 				PGcircle.class, //
 				org.postgresql.geometric.PGline.class, //
 				PGpath.class, //
 				PGpolygon.class, //
-				PGlseg.class);
+				PGlseg.class, //
+				PGobject.class);
+	}
+
+	private static JdbcCustomConversions createCustomConversions(JdbcDialect dialect) {
+
+		SimpleTypeHolder simpleTypeHolder = new SimpleTypeHolder(dialect.simpleTypes(), JdbcSimpleTypes.HOLDER);
+		return new JdbcCustomConversions(CustomConversions.StoreConversions.of(simpleTypeHolder, storeConverters(dialect)),
+				List.of());
+	}
+
+	private static List<Object> storeConverters(Dialect dialect) {
+
+		List<Object> converters = new ArrayList<>();
+		converters.addAll(dialect.getConverters());
+		converters.addAll(JdbcCustomConversions.storeConverters());
+		return converters;
 	}
 }

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/dialect/JdbcSqlServerDialectTest.java

@@ -17,26 +17,58 @@ package org.springframework.data.jdbc.core.dialect;
 
 import static org.assertj.core.api.Assertions.*;
 
+import microsoft.sql.DateTimeOffset;
+
 import java.time.Instant;
+import java.util.ArrayList;
 import java.util.List;
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.data.convert.CustomConversions;
 import org.springframework.data.jdbc.core.convert.JdbcCustomConversions;
+import org.springframework.data.jdbc.core.mapping.JdbcSimpleTypes;
+import org.springframework.data.mapping.model.SimpleTypeHolder;
+import org.springframework.data.relational.core.dialect.Dialect;
 
 /**
  * Tests for {@link JdbcSqlServerDialect}
  *
  * @author Mikhail Polivakha
+ * @author Mark Paluch
  */
 class JdbcSqlServerDialectTest {
 
 	@Test // GH-1873
 	void testCustomConversions() {
 
-		JdbcCustomConversions conversions = JdbcCustomConversions.of(JdbcSqlServerDialect.INSTANCE, List.of());
+		JdbcCustomConversions conversions = createCustomConversions(JdbcSqlServerDialect.INSTANCE);
 
-		assertThat(conversions.hasCustomReadTarget(microsoft.sql.DateTimeOffset.class, Instant.class))
+		assertThat(conversions.hasCustomReadTarget(DateTimeOffset.class, Instant.class))
 				.isTrue();
 	}
+
+	@Test // GH-2147
+	void shouldReportSimpleTypes() {
+
+		JdbcCustomConversions conversions = createCustomConversions(JdbcSqlServerDialect.INSTANCE);
+
+		assertThat(conversions.isSimpleType(DateTimeOffset.class)).isTrue();
+		assertThat(conversions.getSimpleTypeHolder().isSimpleType(DateTimeOffset.class)).isTrue();
+	}
+
+	private static JdbcCustomConversions createCustomConversions(JdbcDialect dialect) {
+
+		SimpleTypeHolder simpleTypeHolder = new SimpleTypeHolder(dialect.simpleTypes(), JdbcSimpleTypes.HOLDER);
+		return new JdbcCustomConversions(CustomConversions.StoreConversions.of(simpleTypeHolder, storeConverters(dialect)),
+				List.of());
+	}
+
+	private static List<Object> storeConverters(Dialect dialect) {
+
+		List<Object> converters = new ArrayList<>();
+		converters.addAll(dialect.getConverters());
+		converters.addAll(JdbcCustomConversions.storeConverters());
+		return converters;
+	}
 }

spring-data-r2dbc/src/main/java/org/springframework/data/r2dbc/convert/R2dbcCustomConversions.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 2018-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.springframework.data.r2dbc.convert;
 
 import java.util.ArrayList;

spring-data-r2dbc/src/main/java/org/springframework/data/r2dbc/dialect/R2dbcDialect.java

@@ -49,7 +49,7 @@ public interface R2dbcDialect extends Dialect {
 		Set<Class<?>> simpleTypes = new HashSet<>(getSimpleTypes());
 		simpleTypes.addAll(R2dbcSimpleTypeHolder.R2DBC_SIMPLE_TYPES);
 
-		return new SimpleTypeHolder(simpleTypes, true);
+		return new SimpleTypeHolder(simpleTypes, R2dbcSimpleTypeHolder.HOLDER);
 	}
 
 	/**

spring-data-r2dbc/src/test/java/org/springframework/data/r2dbc/convert/R2dbcCustomConversionsUnitTests.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.r2dbc.convert;
+
+import static org.assertj.core.api.Assertions.*;
+
+import io.r2dbc.spi.Blob;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.data.r2dbc.dialect.H2Dialect;
+
+/**
+ * Unit tests for {@link R2dbcCustomConversions}.
+ *
+ * @author Mark Paluch
+ */
+class R2dbcCustomConversionsUnitTests {
+
+	@Test // GH-2147
+	void shouldReportR2dbcSimpleTypes() {
+
+		R2dbcCustomConversions conversions = R2dbcCustomConversions.of(H2Dialect.INSTANCE);
+
+		assertThat(conversions.isSimpleType(Blob.class)).isTrue();
+	}
+}

spring-data-r2dbc/src/test/java/org/springframework/data/r2dbc/dialect/PostgresDialectUnitTests.java

@@ -18,6 +18,8 @@ package org.springframework.data.r2dbc.dialect;
 import static org.assertj.core.api.Assertions.*;
 import static org.assertj.core.api.SoftAssertions.*;
 
+import io.r2dbc.postgresql.codec.Box;
+
 import java.util.List;
 
 import org.junit.jupiter.api.Test;
@@ -55,6 +57,7 @@ class PostgresDialectUnitTests {
 			it.assertThat(holder.isSimpleType(String.class)).isTrue();
 			it.assertThat(holder.isSimpleType(int.class)).isTrue();
 			it.assertThat(holder.isSimpleType(Integer.class)).isTrue();
+			it.assertThat(holder.isSimpleType(Box.class)).isTrue();
 		});
 	}