Fix String index out of range when wrapping an char

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/CharacterJavaType.java

@@ -62,7 +62,10 @@ public class CharacterJavaType extends AbstractClassJavaType<Character> implemen
 		if (value instanceof Character) {
 			return (Character) value;
 		}
-		if (value instanceof String) {
+		if ( value instanceof String ) {
+			if ( value.equals( "" ) ) {
+				return ' ';
+			}
 			final String str = (String) value;
 			return str.charAt( 0 );
 		}

hibernate-core/src/test/java/org/hibernate/orm/test/type/CharacterTypeTest.java

@@ -0,0 +1,87 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later
+ * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
+ */
+package org.hibernate.orm.test.type;
+
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.Id;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+@DomainModel(
+		annotatedClasses = CharacterTypeTest.TestEntity.class
+)
+@SessionFactory
+public class CharacterTypeTest {
+
+	@BeforeEach
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					TestEntity dataTypes = new TestEntity( 1, ' ' );
+					session.persist( dataTypes );
+				}
+		);
+	}
+
+	@Test
+	public void transientTest(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					TestEntity d1 = session.find( TestEntity.class, 1 );
+					assertNotNull( d1 );
+					assertEquals( ' ', d1.getCharacterData() );
+					d1.setCharacterData( null );
+				}
+		);
+
+		scope.inTransaction(
+				session -> {
+					TestEntity d1 = session.find( TestEntity.class, 1 );
+					assertNotNull( d1 );
+					assertNull( d1.getCharacterData() );
+				}
+		);
+	}
+
+	@Entity(name = "TestEntity")
+	public static class TestEntity {
+
+		@Id
+		private Integer id;
+
+		private Character characterData;
+
+		public TestEntity() {
+		}
+
+		public TestEntity(Integer id, Character characterData) {
+			this.id = id;
+			this.characterData = characterData;
+		}
+
+		public Integer getId() {
+			return id;
+		}
+
+		public void setCharacterData(Character characterData) {
+			this.characterData = characterData;
+		}
+
+		public Character getCharacterData() {
+			return characterData;
+		}
+	}
+
+}