HHH-17687 Add test for issue

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/converted/converter/AttributeConverterAndNullTest.java

@@ -0,0 +1,119 @@
+package org.hibernate.orm.test.mapping.converted.converter;
+
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.AttributeConverter;
+import jakarta.persistence.Convert;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import jakarta.persistence.Query;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+@DomainModel(
+		annotatedClasses = {
+				AttributeConverterAndNullTest.TestEntity.class
+		}
+)
+@SessionFactory
+@JiraKey("HHH-17687")
+public class AttributeConverterAndNullTest {
+
+	@Test
+	public void testSelectByConnvertedField(SessionFactoryScope scope) {
+		TheField theField = new TheField( "field1" );
+		TestEntity testEntity = new TestEntity( theField );
+		scope.inTransaction(
+				session -> {
+					session.persist( testEntity );
+				}
+		);
+
+		scope.inSession(
+				session -> {
+					Query query1 = session.createQuery( "FROM TestEntity WHERE myField = :myField" );
+					query1.setParameter( "myField", theField );
+					System.out.println( query1.getSingleResult() );
+				}
+		);
+
+		TestEntity testEntity2 = new TestEntity( null );
+		scope.inTransaction(
+				session ->
+						session.persist( testEntity2 )
+		);
+
+		scope.inSession(
+				session -> {
+					Query query2 = session.createQuery( "FROM TestEntity WHERE myField = :myField" );
+					query2.setParameter( "myField", null );
+					assertThat( query2.getResultList().size() ).isEqualTo( 1 );
+				}
+		);
+	}
+
+	public static class MyFieldConverter implements AttributeConverter<TheField, String> {
+
+		@Override
+		public String convertToDatabaseColumn(TheField myField) {
+			if ( myField == null ) {
+				return "null";
+			}
+			return myField.getaField();
+		}
+
+		@Override
+		public TheField convertToEntityAttribute(String dbValue) {
+			return new TheField( dbValue );
+		}
+	}
+
+	@Entity(name = "TestEntity")
+	public static class TestEntity {
+
+		@Id
+		@GeneratedValue
+		private Long id;
+
+		@Convert(converter = MyFieldConverter.class)
+		private TheField myField;
+
+		public TestEntity() {
+		}
+
+		public TestEntity(TheField myField) {
+			this.myField = myField;
+		}
+
+		public Long getId() {
+			return id;
+		}
+
+		public TheField getMyField() {
+			return myField;
+		}
+	}
+
+
+	public static class TheField {
+		private String aField;
+
+		public TheField() {
+		}
+
+		public TheField(String field1) {
+			this.aField = field1;
+		}
+
+		public String getaField() {
+			return aField;
+		}
+
+	}
+
+}