HHH-13974 FlushMode set through SessionBuilder was never applied

hibernate-core/src/main/java/org/hibernate/internal/SessionFactoryImpl.java

@@ -1162,9 +1162,6 @@ public class SessionFactoryImpl implements SessionFactoryImplementor {
 			this.statementInspector = sessionFactoryOptions.getStatementInspector();
 			this.connectionHandlingMode = sessionFactoryOptions.getPhysicalConnectionHandlingMode();
 			this.autoClose = sessionFactoryOptions.isAutoCloseSessionEnabled();
-			this.flushMode = sessionFactoryOptions.isFlushBeforeCompletionEnabled()
-					? FlushMode.AUTO
-					: FlushMode.MANUAL;
 
 			final CurrentTenantIdentifierResolver currentTenantIdentifierResolver = sessionFactory.getCurrentTenantIdentifierResolver();
 			if ( currentTenantIdentifierResolver != null ) {

hibernate-core/src/main/java/org/hibernate/internal/SessionImpl.java

@@ -255,6 +255,8 @@ public class SessionImpl
 		// NOTE : pulse() already handles auto-join-ability correctly
 		getTransactionCoordinator().pulse();
 
+		// do not override explicitly set flush mode ( SessionBuilder#flushMode() )
+		if ( getHibernateFlushMode() == null ) {
 			final FlushMode initialMode;
 			if ( this.properties == null ) {
 				initialMode = fastSessionServices.initialSessionFlushMode;
@@ -263,6 +265,7 @@ public class SessionImpl
 				initialMode = ConfigurationHelper.getFlushMode( getSessionProperty( AvailableSettings.FLUSH_MODE ), FlushMode.AUTO );
 			}
 			getSession().setHibernateFlushMode( initialMode );
+		}
 
 		if ( log.isTraceEnabled() ) {
 			log.tracef( "Opened Session [%s] at timestamp: %s", getSessionIdentifier(), getTimestamp() );

hibernate-core/src/test/java/org/hibernate/internal/SessionBuilderFlushModeTest.java

@@ -0,0 +1,41 @@
+package org.hibernate.internal;
+
+import org.hibernate.FlushMode;
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.boot.MetadataSources;
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+
+import org.hibernate.testing.TestForIssue;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameter;
+import org.junit.runners.Parameterized.Parameters;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author Michael Spahn
+ */
+@TestForIssue(jiraKey = "HHH-13974")
+@RunWith(Parameterized.class)
+public class SessionBuilderFlushModeTest {
+
+	@Parameters
+	public static FlushMode[] parameters() {
+		return FlushMode.values();
+	}
+
+	@Parameter
+	public FlushMode flushMode;
+
+	@Test
+	public void testFlushMode() {
+		try (final SessionFactory sessionFactory = new MetadataSources( new StandardServiceRegistryBuilder().build() ).buildMetadata().buildSessionFactory()) {
+			try (final Session session = sessionFactory.withOptions().flushMode( flushMode ).openSession()) {
+				assertEquals( flushMode, session.getHibernateFlushMode() );
+			}
+		}
+	}
+}