HHH-19698 Fix parsing of in list predicate with null literal

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

@@ -34,6 +34,6 @@ public static boolean isTemporal(JavaType<?> javaType) {
 	}
 
 	public static boolean isUnknown(JavaType<?> javaType) {
-		return javaType.getClass() == UnknownBasicJavaType.class;
+		return javaType == null || javaType.getClass() == UnknownBasicJavaType.class;
 	}
 }

hibernate-core/src/test/java/org/hibernate/orm/test/query/hql/InTests.java

@@ -0,0 +1,33 @@
+/*
+ * 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.query.hql;
+
+import org.hibernate.dialect.DerbyDialect;
+import org.hibernate.testing.orm.domain.StandardDomainModel;
+import org.hibernate.testing.orm.junit.*;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@DomainModel(standardModels = StandardDomainModel.GAMBIT)
+@SessionFactory
+public class InTests {
+
+	@Test
+    @Jira("https://hibernate.atlassian.net/browse/HHH-19698")
+    @SkipForDialect(dialectClass = DerbyDialect.class, reason = "Derby doesn't like null literals in the in predicate")
+	public void testInWithNullLiteral(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+                    assertEquals(0, session.createQuery("select 1 where 1 in (null)", Integer.class).list().size());
+				}
+		);
+	}
+
+}